I agree that many schools don't value languages. Many don't push a language at GCSE that hard now, despite ebacc and because they know that results are often not that good and weaker students find them hard. If few students take GCSE languages, then schools hire fewer language teachers (which are hard to get too) and then fewer different languages can be offered - a bit of a cycle.
Really - made to choose History or Geography in Yr 7 or before GCSE? never heard of that before. When did they have to choose? Did it mean they couldnt do both for GCSE?
With Ops situation, it sounded to me that people were asked to express preferences and also to give any reasons relevant to those preferences. I think lots of schools do this. Op sounds like she gave some valid reasons, and given that some students were put into classes doing Spanish, it would seem she could have been put into one of those classes. There may have been others who also expressed a preference for Spanish but gave no further reasons.
If a school asks for further information and says it will be considered, then I really think they should consider it.
I can see that once everyone has been told their classes and allocations, it is difficult then to swap people around and it would be unfair to ask someone else to swap. However, given that OP gave lots of info as early as possible in the process and more than once, it sounds to me as if the school perhaps just ignored that info and perhaps a timetabler who didn't have access to all of this communication from OP, made the allocations and issued the info. This kind of thing happens a lot - people making decisions and allocations don't have all of the communications about it, which may have gone to another person and not been passed on. I think it is this which OP is annoyed about.
And I can see why school don't want to set a precedent of allowing swaps after allocations, because it open the floodgates. I suspect that they won't meet with OP partly because they are the kind of school which isn't interested in engaging with parents, even though they refer to individualised learning (ha ha) but also because they know this will be hard to explain and justify - OP gave clear reasons for the preferences before the allocations were made, and these were seemingly ignored. Sounds like a mistake to me, and one they D probably won't admit to.
Regarding pushy parents swaying schools and getting their own way....well, if having received the allocations, but never having said anything previously about the reason for the choices or the importance of it for DD, the OP suddenly started demanding change and being shirty, I would agree it was unacceptable and the school should stand firm. However, this was clearly not the case and OP had communicated clearly. Schools often talk about wanting to be in partnership with parents and to have good communication - well Op has tried to do that and the school has resisted attempts to cooperate. If I found myself in this situation, I would feel annoyed and push for a meeting and not settle for being fobbed off.