I think it's because they are two syllables. After a short time objects named after people* (Carnegie Mellon, FDR Drive etc) tend to lose the association with the person so honored and just become strings. This is doubly so for names of international scope.

Think of Google, Facebook, Netflix, Workday, Coinbase: two syllables, each name an iamb (which is especially effective in English). Sure, there are numerous counterexamples (microsoft, Amazon), but generally the corners get knocked off and even turn into acronyms in public usage (GM, GE).

Single syllables are too short for infrequently used words (this appears to be true for any language) -- you don't want to waste a lot of time saying "am" since you say it a lot; when you say "biceps" you want enough variability that your brain has time to parse it.

Webb is a much more common surname than Hubble.