Well, these Baker coin starts are probably going to advantage first player anyway. And let's say it's a particularly pro-first player board to start with. Second player may want to bank on TMap collision decently often, then.
Yes, it is scary that P1 can always get a $5+ Attack card in the opening. IGG/X is always available, get that Curse in before the shuffle, people!
While I like the extra options this mechanic provides to the players, I'm scared about the effects it has on "pro" play and how much more it will swing the balance into P1's favor.
That being said, we have to agree that Dominion never intended to be a "pro game" (like Magic for instance). It turned out that way because people started to take it seriously and we were offered a very good online platform for it. If Iso never had existed and we could only play unranked games on BGG, I don't think this would be an issue at all. And of course all of the expansions have been designed without thinking that players will just play a single match and move on.
The effect of first player advantage is lessened in real life by making the player to the left of the winner go first the next game and you could get 3 games in with different cards in the same time as it would take for a regular worker placement. I still enjoy real life play the most, but unfortunately I rarely have the time for it and online is a decent surrogate.
All in all I think we have to accept that there will be cards which don't care a lot about the effect they have on pro games and the P1 advantage thingy. If they did, there wouldn't be any attacks! I'd rather have cards not care about that and be fun than care about it and be boring.