Since you quoted oddly, I can't quote well either -- your comments in quotes.
"Why do you think so? In a battle your aim should be to beat enemies asap with the cheapest cost possible, weak spells are suited for weak enemies"
Perhaps I'm not being clear -- obviously you're going to use weaker spells against rats, etc. And obviously you use your 'Ice Storm' against fire dragons, and your 'Fire Storm' against Evil Snowmen. That's not what I'm talking about... that's still just picking your most relevant DPS (or buff/debuff) spell against any given enemy or mob of enemies.
That quickly becomes rote. You use the most relevant spell, quaff a potion, and use it again. And again. Where ever necessary, and without thought to scarcity. Why use a thunderbolt against that Ice Giant when you're obviously just going to use Greater Fireball? Spell quantity limitations force you to be very selective, and often use spells that might not be the 'best' for a given situation. If you only have 1 Greater Fireball left, do you use it against that Ice Giant? Or save it for a later enemy? Do you use a Thunderbolt against the Fire Demon because you really need to damage him and you're out of (or don't want to waste) Ice spells? Or just risk letting your melee characters whittle him down?
In a mana based game, of course you use the best spell available (in this case your elemental spell of choice), then you quaff a potion, no big deal. Ice Storm, Thunderbolt, etc, are 'options', but not 'choices' --- that is, the choice is obvious.
"imo a well balanced game without mana potions would have anti poison spells or potions, not both because having both would defeat the purpose of not having mana potions"
Many games have scrolls and potions that emulate important spells. You have antidotes to use for 'remove poison' spell, a Phoenix Down type item (or church) as well as revive spells... many games also sell scrolls so non-magic users can 'cast' limited spells. And then you have 'horns of fire' or 'swords of laser' to further emulate magic.
There are very, very few games that don't have easy to replenish mana points in mana based games. The only one I can actively think of is Bard's Tale 3, in fact... though I'm sure there are more, where you had to wait 'real time' for mana to restore. All the rest I can think of have potions or ways to easily rest, though I may be forgetting some others.
However, that's sort of the point -- limiting mana forces hard choices. I like that. So I'm not criticizing those games at all, merely pointing out that in the vast majority of mana based games your spell casters are effectively mana-rich by mid game due to stockpiling potions. And once you are mana-rich, there's little need to conserve mana or put much thought into what spells to cast/not cast.
"Again the game should give you a motivation to use a spell, why should i use the greater fireball in a dungeon full of weak enemies with low resistance to ice?"
See my first response... I made the mistake of assuming that was a 'given' in making my point -- obviously you use 'Ice Storm' or 'Fire Storm' where appropriate. But that is not real choice between spells, it's just rote behavior.
The issue is purely that it doesn't matter if you cast that spell, because you just quaff a potion after the battle. Spell limitations force you to evaluate each and every cast and it's risk/reward.
"again it's a balance issue, if a game gives you ice, fire, earth and other elements then they should have a sense, every enemy should be weak or strong to something, if most of the enemies are neutral to elements then there's no point to them, what to use is just a matter of preference."
I don't view the choice between casting Fireball and Iceball as 'choice', if all I need to do is drink a potion afterwards. That's not 'choice'. You just pick the relevant one and you're done. That's the illusion of choice.
If you only have 5 fireballs left, and you're 6 levels deep in the dungeon, the very act of casting a spell becomes real, true, choice.
What you call 'freedom of choice' I call the opposite -- if I have the mana and can easily replenish said mana, I'll always pick the 'best' spell. That's not real 'choice' as I define it, because my choice becomes a given.
"No matter the magic system and the balance there will always be spells that are more useful than others(attack spells will always be used more than resist spells), it's inevitable, that's why a game should not limit choices"
Totally disagree. If you have unlimited spells and unlimited mana (via potions) there's simply no reason to think about what you are casting, you just cast the most obvious spell for the situation (fireball against ice, etc). That's just a given. It's not actual 'choice'.
Actual 'choice' almost requires limitation, there must be a serious consequence. Spell limitation achieves that.
"It would be the same with a well balanced game with limited mana or whatever the system, always using greater fireball is developers' fault, not magics' system."
You're focusing on my example, which is my fault. I should have been clear that's only an example. You will always have a best DPS spell for any given situation. If you are mana rich, and mana is cheap to replace (as it always is) there is little reason not to spam that spell. It really is that simple.
"IIRC even in certain dungeon crawlers with D&D system there's a way to refill spell uses, so it's not that different."
Well, yes, there must be a way to recharge somehow. Some force you to leave the dungeon. Some don't.
But... If it's not that different, why skip this game?
Perhaps the easiest way to explain what I'm getting at... say a game only provides you a single 'Greater Fireball' between rests (so, 1 per battle). Against a huge demon, you'll use it once... and then go through your other spells. In a mana-rich/potion game, you can just spam that 'best spell for this situation' over and over, quaffing potions (or whatever the best dps combo is, it could be spamming Medium Fireball because you get 3 per potion, the specifics are immaterial).