I think maybe people are forgetting that building donk decks are a strategy. A strategy that is based a whole lot on luck, but it's still a strategy nonetheless, and that's basically how Pokemon works. There are attacks like this is Pokemon, where your Pokemon has to go all in, and take a chance with a super-risky attack. The deck built to donk is simply a TCG version of that.
If you get donked, it doesn't mean the other player has no skill, and just got incredibly lucky. It just happens; it's part of the game. At a City Championship last weekend, I lost my 2nd round to a player who was just starting to play. I got a bad start, only got an Uxie and they got 2 Donphans rolling before I could get any cards that would help me. That doesn't mean that they were purely lucky; they knew how to play their deck and they played as well as they were able to. 2 rounds later I went toe-to-toe with Gyarados/Donphan and won, despite it being my deck's weakness. It's just going to happen, and short of banning every card that does more than 20 damage for 1 or 0 energy and giving every Pokemon 80+ HP, it's going to keep happening.
Even if a player was able to call a mulligan because they only have a single basic, the chance they'll redraw and only get one basic again is still there. Are you going to let players continually shuffle until they get the setup they want? If you institute a max number of mulligans is t still fair if they still only get one Pokemon on their last reshuffle?
I don't like playing archetype decks. I go rogue whenever possible, I think playing SP is just playing on autopilot, and getting whipped in three turns isn't really my idea of a good game. I think outside of one or two very specific conditions, going first is extremely detrimental to most players. But that's just the nature of Pokemon. There are always decks that you are not going to want to play against, and you'll have to play against them in tournaments. What do you do? Tech your deck against them. Donks aren't going away, and if POP were able to ban donks outright, some other style of deck will take its place.
I suppose the point I'm trying to make is that the Pokemon playing field is quite possibly the most diverse it's ever been. This is a really good thing, and based on what's coming out, it's going to really open up after the next rotation. Donks won't be as big of a problem, but there will always be something to take its place.
One last thing: It does suck if you get donked in a tournament, but imagine how the other player feels when you declare 'you only won cos you donked me'. The other player probably wanted a long battle, wit clashing against razor-sharp wit, but if the opportunity arises, especially in a tournament, you're going to tell me you wouldn't go for it? At the end of the day, Pokemon IS just a game after all.