Amen. You said it all.I completely agree with the main point. I constantly see this situation on many forums where people buy fish knowing full well it will get too big with the 100% intention of just swapping it for a smaller one when it does.
It also should be noted that the comment of "My fish looks completely healthy" is irrelivent. There are situations such as stunting where you can't physically "see" the problems it's causing. Also there is a fact that unless you put the same fish side by side, one in correct conditions and one not, you really won't be able to recognize behavioral issues. Unless you have previous experience with that fish being kept properly and you know how they are supposed to act.
I agree in small portion about the emotional attachment to fish. However, this is probably due to the amount of people keeping fish improperly. When fish are kept in proper conditions I feel they are much more apt to show personality. My fish will swim towards the glass and show off when I'm in front of the tank watching them. My bettas will swim right into my hand when I'm in the tank. I could literally just scoop them out with my hand. You can teach them to feed out of your hand. They have just as much personality as many other pets when kept in proper conditions.
I also think research is a must at all times. But you only know that AFTER you've screwed up so many times that you go looking for reasons why. I do have to place a decent amount of blame on the pet stores. Even for people willing to learn. I tried a couple years ago to get into fishkeeping. Went to several stores before buying anything. Asked many questions to various workers through various stores. Got the same BS answers from all of them, was never told jack about cycling or anything like that. I'm sitting there thinking I've done research, asked around multiple places, and because they want to sell me fish they all either lie or have no clue what they are talking about. So I got a tank full of fish that died and it discouraged me from getting into the hobby until about 6 months ago. I finally thought I would search the internet since I never really was able to keep fish alive previously. My eyes were opened no doubt. NONE of this information was provided ever by an employee. Even when they partially know what they are talking about they only know half the answer. It's crazy.
Sorry for the long post. Some venting, some reinforcement of the major issues in the fishkeeping industry.
That's my 2c,