I tend to disagree with you on a few points here.
Before the mage rework, I would often not buy a
because I would be going up against a mostly all AD team comp. Does that make me a bad player? I don't think so, it's about itemizing for the situation (I would often play supports like Ali or Braum so things like sunfire and frozen heart).
I also disagree with you about the gold part. Forcing me to go and buy a Locket or ZZ rot or something, is a huge deterrant from playing support because I have the least amount of gold and those items are extremely expensive. In a game where there are low kills or we are behind, it's often the case that I have 2 partial items bought but not enough money to finish them. Personally, I feel that the support items are pretty much garbage, but I build them because they are cheaper than most items and it gives me a bit of a power spike. Aura items have the same problem that the old Taric ult had, they feel very underwhelming. Whereas if I bought straight AP, I can feel that difference immediately. But that's a problem for another discussion.
Finally, I just have to disagree with you about team comps. If we have a team with let's say a Malphite top and a Rammus jungle, I'm going to build sightstone and then straight AP (I'm kinda having a fling with support annie atm). With a team like that, we have enough engage and enough tank where I feel comfortable going and APC build. Me not having a locket or zz rot isn't going to be detrimental to the team, I would be doing more damage, which a team also needs. I agree that this isn't for every game ever, but going full AP is not going to kill your team comp or cause you to lose the game outright.
Where I do agree with you are these two points. Starting a support item is key, but I really don't want to finish that item most of the time (but I do because it's cost). Second point is that the bot lane sucks right now. Supports will be bad to play, no matter what game you play (personally, I think its because most people want to do a lot of damage and be the "hero"), but ADCs are in a real shit place right now.