I believe it's done purely for business/logistical reasons not basketball reasons, so I don't think it really matters if it doesn't favor the higher seed.
While it's not as bad this year with it being OKC vs Miami, think about if OKC was still located in Seattle, or if it was Miami vs LA, or Boston vs LA, or any East Coast team vs any West Coast team, and all the people covering the finals, and what not.
In a Seattle vs Miami 7 game series scenario (which is pretty much the worst possible scenario traveling within the continental US):
Miami would fly to Seattle for 2 games.
Then both teams would fly to Miami for 2 games.
Then both teams would fly back to Seattle for 1 game.
Then fly back to Miami for 1 game.
Then fly back to Seattle for 1 game.
Then Miami flying back home afterwards.
That's the away team flying cross country 6 times, and the home team flying cross country 4 times in a 2-2-1-1-1 format. But with the 2-3-2 format the away team would only fly cross country 4 times, and the home team 2 times. Door-to-door that could be like an 8-9 hour trip across 3 different time zones. You want to do that as little as possible.
That could be a lot of cross country flights. And it would be tough for the players if there was only one day off between certain games, like with the Sunday, Tuesday, Thursday stretch, think if that coincided with games 5-6-7. sure you'll say the NBA should change the Sunday, Tuesday, Thursday format, but that's another thing done for "business" reasons that they won't change.
And don't just think of the players traveling, but the coaches, assistants, trainers, staff, and the hundreds of media outlets (like the low-budget local news papers/stations, and even international outlets) who cover the games too.
Also, the travel isn't as big of a deal between say a Boston/Philly or Miami/Orlando or Dallas/San Antonio or a lot of other potential inter-conference series, and there is also only a fraction of the media coverage so the 2-2-1-1-1 format works better in the 1st round, conference semis, and conference finals, but not so much for the finals with the potential travel.
So screw the slight advantage to the lower seed, it's done purely for business reasons.