Blue was an interesting idea, in that starting the game with such a battle, with two lvl. 5 Pokémon against each other and only two moves each, was a strange way to make players interested in the thing, and makes Oak suspect because they just gave you a Pokémon and then indirectly forced you into a battle. This battle was then in many ways subject to what the game would refer to as 'luck,' or their being quite able to do things differently. People might have gone along with it because they assumed that everyone was going through that, but it does make all of the enthusiasm about 'Pokémon' as such seem suspect, especially since they didn't even need to pick the stronger Pokémon by type (which is an unnecessary move in the context), although their doing so is, again, a fairly annoying move - and, as we know that the games enjoy bringing up and explaining type differentials, seems designed to denigrate the choice of starter before people started doing anything. While it wasn't generally a difficult battle, it does seem to conflict with much of the game's publicity. But yeah, so, that's as to their chosen introduction into the gameplay.
Anyway, though, other than their being a gameplay element - which seems a slightly circular issue of 'this is Pokémon, you fight your 'rival,' then head up to find a gym leader named Brock for some reason (followed by a Misty, a Lt. Surge, then a plant gym, etc.),' before it's been established that having a rival is just something that people do in Pokémon games - they don't have that much character and that had to be supplanted by Gary Oak in the anime, seemingly. It does somewhat highlight that Blue is generally quite co-operative, though. Their Pokémon are generally speaking not that coherent a formation, and hence also reacts to the player in certain ways, but speaking of these they do basically come across as the game trying to imitate the player in their substantive decisions. People may have found it disorienting that such a character was just tagging along with them, and do seem to still be a bit quiet about such things. It does seem strange that in a sense the player isn't supposed to leave Pallet Town, and in a sense isn't told that they have to, which gives you your Pokémon, map of the rest, your target in terms of the Pokédex, your target otherwise, etc. - what is the rest pointing to, then? It seems a bit convenient that after saying that all of the stuff in Pallet Town is a 'pointer' to everything else that happens in the game, the battle with Blue turns out to re-occur near the end-game (admittedly before catching a Mewtwo elsewhere), which makes you question whether they needn't have just stopped there before throwing near-identical battles at you and the occasional Pokémon to catch. Still, he does somewhat make the game itself feel more sedate, rather than the more hectic progression it may well be otherwise inclined to take, and hence serves as a source of continuity.
The fact that people dislike him means he successfully achieved his goal as an antagonist, from a written perspective, which is to be disliked.
Other than this isn't the WWE, if people dislike him as such, as in want him out, then they are criticising the game they aren't part of its real purpose. This can apply just as much to an antagonist as a protagonist, they aren't different in this (and it's a bit presumptuous to claim that the game thinks that highly of its 'protagonist,' namely the player, who could be anybody). Then they're just disliked, as a character, even if the 'protagonist' of the game has mixed feelings towards them.
I don't think you'd call him 'snarky,' the word more associated with their negative traits was 'smarmy.' Anyway, you could've just said so if you wished to complain about their behaviour or its compatibility with the world of Pokémon (which mostly just sits there and lets Blue do 'mean' things seemingly without reacting, which doesn't make it seem too worth that bother), but bringing this complaint in question as such seems a strange way to reach that goal.
