The "no infinite experiment repeats" sound like they're going to make science a lot more painful to happen. No more queueing up dozens of transmissions simultaneously while passing through high atmosphere. Also, no more gathering science from multiple sciomes with the same vessel
Actually, it sounds like instead of repeatedly transmitting from 1 biome, you will be able to gather multiple biome experiments with 1 vessel as long as you collect and store with EVA. Much better then repeatedly mounting slightly different missions to the same planet.
Take for example a Science Jr, and land it on Eve. If you bring an antenna and a solar panel, you can get 20 transmissions each from Kerbin's surface, low/high Kerbin atmosphere, low/high Kerbin orbit, high over the sun, high/low Eve orbit, high/low Eve atmosphere and Eve's surface. That is a fuckton of science you get there: around 1900, using just the Science Jr.. I unlocked almost the entire tech tree in only six missions (landing pad sample, Mun orbit/return, Mun landing/landing/return, Minmus landing/return, a Moho orbit and an Eve landing), and I don't see how that's grindy at all, since I don't really need to go to the same place twice. Now imagine how much science I would not be able to gather at once if the science modules weren't infinitely resettable (or at least not without the occasional EVA). I couldn't do the atmosphere samples, I'd need to EVA a few times in every other sciome, and the science I'd get from Moho or Eve would be further decimated because I can't return the science completely. This would essentially mean that I wouldn't get enough science on the first trip to the planets, necessitating second and third trips just to get enough science to unlock the necessary parts for the fourth and fifth trips. I really don't see how that's better than before.
I don't think you are getting how broken the current system is.
Right now, there is NO reason ever to return anything, you can just spam transmission, and suck up all the science from whereever.
This leads to stupid stuff like 5000 science with only a few parts unlocked.
I want to stress that there is NO penalty to transmission, you just have to do it a bunch of times over and over.
I have yet to meet a person that thinks it fun to spam transmit on 6 different science modules, 20 times during a mission.
The new system will make it so there is a portion of science reserved for bringing it back to Kerbin. That way you can still transmit science, but there will be a reason to make a return craft.
To fix the system for myself, I don't allow transmission of anything but crew reports(which is intended to be transmitted), and tiny bits a science like 3 science from a goo container.