The templates do not provide any additional possibility of proclamation that plain text on the user page wouldn't already provide. Since you agree that the declaration of a point of view on a user page is not in itself wrong, it logically follows that the mere fact that the templates proclaim a point of view does not make them wrong.
Some of them were blatant trolling, of course. Others are informative but irrelevant to the process of building an encyclopaedia.
They are no more irrelevant to the process of building an encyclopedia than most userpages already are (take mine, for example). Yet nobody calls for the deletion of those userpages on the grounds that they are "divisive" or "inflammatory".
It is highly doubtful that any significant amounts of server resources are at stake. It is even more doubtful that the load would be significantly increased compared to the current situation which already allows a significant number of humorous (and therefore irrelevant) userboxes. Either way, a proper analysis of the consumption of server resources has not been made.
Nor does it need to be since the benefit to the encyclopaedia is zero and the cost non-zero.
It is doubtful that the cost is greater than that of having userpages. Quite to the contrary, using categories and "What Links Here", the userboxes produce semi-automatic organisation and structure. This reduces cost.
There is nothing about the templates that makes them any more "officially sanctioned" than text on a user page on a Wikimedia-controlled server already is.
So you say. Others disagree. A Template space userbox which is listed in a directory of userboxen appeared to many to imply precisely that: "official" support for divisive userboxen.
The argument is irrelevant (because, as I already pointed out, it equally applies to userpages, a list of which can be created on [[Special:Allpages]]). It is the typical kind of argument people come up with hastily when they're just looking for something to corroborate their theory or to further their goal.
A proclamation of any belief is possible without breaching any of those two requirements (not being inflammatory and not using non-free images).
It's a separate issue right up to the point that someone has to make a judgment call about *your* particular userbox. Some felt that the endlessly protracted decisions on each individual userbox (is it divisive to say that you accept or reject Ayn Rand's philosophy?) were an even worse use of time and resources.
It is odd that, instead of precluding those "endlessly protracted" discussions, you think you are solving the problem by instead forbidding certain userboxes entirely, while it is plainly obvious that this controversial prohibition causes a lot more discussion. There is nothing wrong with a userbox stating "This user accepts Ayn Rand's philosophy" -- there is, rather, something wrong with someone going "OMG this userbox is divisive, it must go!!" So prohibit the latter.
Timwi