I agree. These are actual living beings, vertebrates no less, and I imagine there are quite a lot of unhappy fish sulking about in aquariums. After all the tanks we provide for our fish is their entire world, and as their captors, or gods really, I think it's our responsibility to provide them as adequate housing as possible. And when a fish gets larger than a certain point that simply isn't possible for most people, often not even in the largest public aquariums. There is one such public aquarium in Denmark where they have a sunfish which is so supposedly fantastic, while I just think it looks terribly sad. Same goes for the sharks they keep. Creatures that are literally supposed to have the entire sea to explore reduced to living curiosities.
I don't think larger species should be restricted for sale simply for being large, as more laws are seldom a solution unless it's concerning pressing matters such as invasive species. Perhaps more importantly it would acknowledge the fact that fish have feelings in a way that many governments and people won't readily acknowledge, as an eventual law would be purely for the well-being of the fish, which might bring other matters up for discussion. Fish all over the world are having a seriously hard time as a direct consequence of humanity, and although much of it is being brought to light such as sharks getting their fins cut off, other matters still are not commonly discussed and some times best not discussed. Take for example the food fish farming industry. Here in Norway we have what is best described as giant cages in the sea and sometimes lakes, where we breed species such as Salmon and Trout to be eaten. These fish are really constrained, and really densely packed. The sea provide filtration so you can really stuff quite a few in there. The sad truth is that fish farming will become more and more necessary, and while somewhat cruel it's far better than sourcing fish and indeed meat by traditional means. So where exactly do we draw the line? What is right and what is wrong? I think the bigger species shouldn't really be in any stores, and only available through order. It would nearly eliminate the possibility of impulsive acquisition, while still being available for those who absolutely has to have one.
I don't hold anything against anyone who keep larger species, and don't have any strong opinions where other people are concerned. That being said I try to provide as comfy surroundings as possible for my fish, something that might prove quite the project now that I have two Gars in addition to my Polys, Ery and Channa.