I'm fine with the limit. Not 'cos of backwards compatibility, but human readability. A:
"Minifig Helmet with Hexagonal Top, Hoses, Silver Alien Pattern" - 62 characters
gets you a good picture what this part is about. I cannot see any benefit in:
"Minifig Castle Helmet with Hexagonal Top with Hoses, Buttons, lots of Yellow Stripes on Green Background and Silver Alien Pattern" - 129 characters
w.
"Minifig Helmet with Hexagonal Top, Hoses, Silver Alien Pattern" - 62 characters
gets you a good picture what this part is about. I cannot see any benefit in:
"Minifig Castle Helmet with Hexagonal Top with Hoses, Buttons, lots of Yellow Stripes on Green Background and Silver Alien Pattern" - 129 characters
w.
LEGO ergo sum