Aside from "I lost to Boggles once and I felt sad" or "I still feel salty about Invisible Stalker even though its a clear mistake that hasn't been repeated since" I don't know why anybody would want Shroud back. In a world where creatures and creature combat is more important than ever and control decks no longer fall to one random "hard to deal with" dude, Shroud is a negative mechanic more often then not. Algea Gharial would be an offensively bad card if MM2 was designed like any modern limited format, Cube, was in a casual context or whatever. I agree Hexproof is a mechanic, like many others, that WOTC has to be careful with but considering they have been careful with it for the past however many years I feel people can cool it with the whining.
I sort of feel the same way, but less intense. I don't particularly find hexproof to be annoying, save for the fact that it just shouldn't exist in blue whatsoever. Instead of getting rid of hexproof, I don't see why they don't try moving it completely out of blue and making some decent edicts in any set with hexproof as a feature. If they just don't make hexproof as something that can't be dealt with, it's not all that annoying. But having it a color that lives to drop a creature and then counter anything you throw at it and having no real spells to answer it is where it gets annoying.
I think hexproof is sort of necessary in green as a way to avoid "Tap 2, kill your 6 mana creature." Green lives off of big creatures, pump spells and auras. If you take those tools away, what's the point of green in a world where white, red, black and blue has cheap creature removal and green just doesn't?
To be honest, if they made cheap, efficient indestructable creatures in blue, in a set with no exile effects and suddenly made it a blue keyword, well, that would also be an issue. Hell, maybe even more so since wipes don't affect those. But since indestructable is almost always on an expensive, unplayable white creature, its never really been a problem. (That I can think of right this second).