I think you might be over blowing it just a little bit you have to keep in mind the differences in the game. Oracle or dazzle would be either too complicated or too powerful in the hots environment. Having every ability available at lvl one as well as the extremely team fight orientated nature of the game is so vastly different then dota, and like Maledict mentioned that's not necessarily a bad thing.
This is a good point but every other hero has every ability available at level 1. You obviously can't give heroes mind-numbingly powerful combinations that are available at level 1, you have to introduce them through the talent tree. The problem is that they really don't use the talent tree that way. And when they do, you get talents that are must-picks and other talents that are complete garbage in comparison. Gathering Radiance and Righteous Defense are both really cool talents but they both sit there on a tier with Benediction and Benediction is an ability that (a) is too powerful and (b) the spectator can't even see. Additionally, the talent tree as it currently stands generally favors you picking a build that is greatly focused around one of your core abilities so that the talents themselves synergize with each other. Dunktrain has gone on rants in the past about this, as it pigeonholes you into talenting one ability rather than adapting based on the game. This further constrains talent diversity.
Rehgar's level 13 talents all essentially translate to "heal additional HP." Meanwhile a talent like Totemic Projection, which has interesting gameplay applications both for players and spectators and thus quite a bit of potential, never gets seen because (a) it's sitting on the same tier as Cleanse and (b) it doesn't give any additional raw number output. Even if Cleanse wasn't on that tier, nobody would pick that talent because 2 seconds of cooldown reduction across your whole base kit is way too powerful numerically and vision as a utility (Far Sight) is also way more valuable. So we have a really cool talent that just gets buried because of bad design philosophies.
I think there are good synergies in heroes kits, it's just that there's some abilities that are just kind of meh. Like bright wings nuke or diablos flame stomp or tassadars psi storm, like they don't serve a purpose other then to do general damage in a general area. But I do think there's interesting synergies in most heroes kits, like feral lunge into totem is good. monk is a good example because his whole kit kind of comes together to enable really aggressive dive comps. The problem is as it stands supports can't have too much utility or damage or anything else really because healing is already too damn good.
There are far too many "do some general damage in an area" and "heal some damage on a target" abilities in this game. Tyrande Q, Uther Q, Rehgar Q, Tassadar's Q, it's really dumb. On the topic of Tass, Force Wall is great, but his entire kit and talent tree is a complete disaster. They need to completely remake that hero from the ground up.
They could have more supports like medivh and they absolutely should, but unless they fix healing no one will ever pick them. Being able to instantly erase the enemy teams advantage moment to moment with such little effort is too powerful.
They can tune the numbers down and fix the talents to Allow for more strategy, but it doesn't look like they're interested.
Totally agreed. This game needs heroes like Medivh that enable shit to happen and counterplay the other team's actions rather than just blindly pressing buttons to deal damage or heal (as an aside, however, Medivh's Q is just "click to deal damage" but I digress). On that topic, HOTS is also badly lacking initiation heroes which further contributes to the value of poke and heal. What's the best initiation in the game right now? Muradin jump, ETC slide, Stitches hook, Falstad Fly/Gust, Void Prison, Kerrigan, Sundering. But for example they can't make Sundering too strong because it's sitting on an assassin hero that does a shitload of DPS. So they've chosen to nerf the stun and CD on Sundering because it's on an assassin so that they can keep that hero as an "assassin" that deals lots of damage without being imbalanced. As a result one of the best initiators in the game is no longer anywhere near as impactful.
We need more Tidehunters and Elder Titans in addition to more interesting healing options.