Errolo, I tend to agree except that I would blame the GCSE syllabus which seems to be designed by natural linguists for natural linguists., and bugger anyone else. And seems to assume that all languages need to be taught as if they were Romance languages.
DS struggled with French but enjoyed German. He was at a school which taught German in a very traditional way. He liked the structure and once he had mastered the discipline of learning the set vocab each week, enjoyed piecing together sentences in a mathematical sort of way.
DDs German teaching, at a different school, followed the GCSE approach. Virtually no grammar, so at the end of her first year she had no idea how to conjugate ich bin, du bist etc. Instead she as learning set phrases with no explanation as to the structure behind. Even more bizarre was the approach to the oral. They were told what topics might come up and told to prepare answers to possible questions. There was no teacher input into the answers so DD was essentially learning stuff she had prepared, laden with errors. I speak German reasonably fluently, though don't write it, so was aware that it was wrong. Luckily someone in the group had a bilingual mum who sorted them all out and with me teaching her the grammatical basis for the phrases she was learning and a decent stab at the oral, she landed an A*. Even so DD would be pretty stuck in Germany unless someone wanted an indepth conversation about sperrmull.
DD is pretty dyslexic, so learning support were surprised she was taking languages at GCSE. I have never understood this as I have lived in places where people are illiterate yet speak six or seven languages fluently. Ditto her French is almost certainly better, in terms of being able to communicate, than many with A level, mainly because she came across plenty from Lycee CDG at her extra curricular so they mixed and switched between English and French.
I speak French and Spanish as well, and generally German is best for mathy types. People say it is "harder" but actually harder often poses less of a problem for bright logical kids. As you progress German probably is more impenetrable, because of the sentence structure and noun declensions. But GCSE is fine if taught suitably.
As regards UCL, some courses are really competitive to get onto, including Computer Science, so when your application is scored you want to be able to tick as many boxes as you can. I have no idea how much weighting UCL give having a language GCSE, but assume it might matter for borderline applicants. It presumably will depend on how strong the rest of the application is.