A couple of things. You and I were saying the same things about Dissolve and are continuing to say the same things about Hexproof here. You probably know that, but you worded it in an odd way, just making sure that you're not confusing me with people arguing against either. I think they're both fine.
Oh I know we both agreed then and I think we mostly agree here. My apologies if my word choice threw you off.
Now, we start to diverge when we talk about blue. It has nothing at all to do with hurt feelings about a color or any such nonsense. It is all about how certain keywords become inherently stronger when moved into one color pie. Hexproof in green really hasn't shown itself to be a problem. Sigarda is a problem in EDH, I hear, but I don't really count that as a "real" format when we're talking about card balance and creation.
There is a reason why Hexproof turned an otherwise ho-hum 1/1 unblockable into one of the most hated cards in Standard at the time. There is a reason why Ojutai is a card that instantly became a deck. Hexproof in blue is much stronger than hexproof in any other possible color.
Blue keywords, I'd argue, need more close monitoring than just about any other color. And frankly, with flying, unblockable, autocountering and the like in its toolbox, Hexproof is an unnecessary addition to blue's repertoire. Conversely, it (or shroud) is an absolutely necessary addition to green's toolbox. That's not saying green is a "victim" color, but it's a necessary addition to a color that relies on creatures more than anything else. Hexproof/shroud shore up the gap between the cost of effective creature spells and effective creature removal.
I think "butthurt" describes a lot of people I've encountered online in this discussion but I agree it was harsh to imply that applied to you as well on further reflection. My bad.
Now, I'm aware of how context can change how powerful certain mechanics are in certain colors. There is a reason Red (Burn) and White (many universal answers) don't get much card draw for example. I just don't think the competitive results (which I think matters most for power level concerns) bear out that Hexproof is problematic in Blue. First off, we have to be honest with ourselves, when its comes to Hexproof, the biggest issue is the CMC of the cards it gets put on more than the color. Gladecover Scout and Slippery Bogle are some of the easiest Hexproof cards to interact with but they are likely amongst the strongest considering power level. At two mana, only one more, Invisible Stalker has very little competitive success. Putting absolute evasion and Hexproof on a card that cheap was a mistake but I think its CMC is the biggest offender of that package. Then we move up to like Aven Fleetwing but that card is trash despite having evasion and hexproof.
Of the Blue cards with hexproof, how many have seen REAL competitive play in T2, Modern, etc.? Ojutai, Simulgar 1, Prognostic Sphinx and Geist of Saint Traft I think are the only ones really (Slippery Bogle is "Blue" but mostly played in decks with no Blue cards or sources. Out of all of them, Geist is the strongest because it is the cheapest. Geist + Mana Leak is admittedly a strong combo. However the card is still very easy to interact with using creatures. The card is pushed and very powerful but I don't think its a mistake (or nor more a mistake than any Modern playable creature in any color). I don't see these examples of "Blue can't have hexproof" I just see them as strong cards that every color is allowed to have access to at some point.
As for Blue other keywords, the purpose of Hexproof is to make creatures that are hard to interact with. That's specifically what WOTC wants. Evasion mechanics don't do that and counterspells are limited in number and by opportunity cost. Mentioning them seems irrelevant because they don't serve the same purpose and, as has been proven, evasion + hexproof is fine as long as the card isn't too cheap or the hexproof conditional.
Looking over the past few years, I think WOTC has done a good job managing hexproof in all the relevant colors. The Blue hexproof creatures and the Green hexproof creatures are both good but for different reasons and play in different spaces. They've come to better understand on what kind of bodies and at what kind of mana costs they can make hexproof cards that are appropriately powerful and hard to deal with (i.e. the point) but not super obnoxious. At this point I don't think there is much of an issue and if WOTC decides to fall back, which would only be from pressure due to a lot of whining, I will be disappointed. I actively don't think Shroud plays well today given how creatures are made. I have no interest in shroud creatures for my Cubes, EDH decks, etc. The ability to positively interact with my permanents is too important. As long as WOTC develops the mechanic well, I don't think there is a problem and I think they have done a fine job developing the mechanic. I think the most recent "slip up" was Gladecover Scout but since then its been smooth sailing.
Blue has the self-exiling ability (commonly called "blinking") Well, temporary exiling in general is called "blinking" but you get the idea.
Aetherling plays very differently than Ojutai, Silumgar, Prognostic Sphinx, etc. It's abilites are NOT a "substitute" for hexproof.