I would have agreed completely with OP before this past weekend when I switched to the beta branch. In my first couple 2.2 games after launch, the market was just there and could be used to too-easily fill all the gaps in my production as the prices stayed fairly static.
But I played a game on the beta branch this weekend, and saw a lot of improvement. Specificallly alloys, which I could easily get for (I think) about 12 EC in my first games, were inflated up to consistently 18.3-18.8 EC in the game I played on beta, because so many empires were buying them. It was fluctuating in real time, and every time it dipped to the low 18.00s, it would immediately rise back up to the mid to high 18.00s, cause there was such a run on them.
I went to the market to buy alloys, and it was just too expensive to buy anything more than 250 of them. A couple years later (I gor the FL Ecumenopolis and started produceing lots of alloys) I sold 1500 of them (of my stockpile of 7500) for like 19K EC. And after my sale the alloy price on the market immediately went down to the 16.00s (it was back up to the 18.00s in about 20 seconds as this drop caused another run).
Food and minerals were also going through this, to a lesser extent. Pre-beta, minerals and food were going at about 1:1 (plus minus the market fee) for EC. In beta over the weekend, food was going for about 2.62 and minerals for about 3.00 due to market activity.
FWIW, I don't think there was any rebalancing of market mechanics in the beta, but rather how the AI used the market. Pre beta, in my experience the AI was not really using the market much if at all.
I get what OP is saying about infinite supply (and a "floor" for value), but if it works like it does in my beta branch game, it's actually pretty cool, and with enough empires active on the market the prices are fluctuating enough in real time that you don't really notice this. Granted this is a one game sample size and on the beta branch....