Maple makes me sad. They had an amazingly effective streamlined GUI circa 2000, a native Windows app which launched significantly faster than the built-in Microsoft calculator tool, and then felt like an upgraded terminal-style REPL with all of math at your fingertips. It had capable plotting with nice embedded graphics, great built in documentation with fast search, etc. It was rock solid, I don’t think I crashed it once. As a high school student, it was an amazing tool for me.
Then they decided to hop on the Java bandwagon, and rewrote their whole UI using some kind of cross-platform Java GUI toolkit. App startup time went from like a tenth of a second to like 30 seconds (at least, that was my subjective impression at the time). Every part of the GUI was laggy and glitchy, it crashed regularly, the documentation was reorganized and much more confusing, etc.
The big-ticket feature additions which supposedly justified the rewrite were some gimmicky stuff for writing formulas in a more standard-math-typography way instead of as plain text, plus some related handwriting recognition thingy, but this ended up being slow, confusing, and ineffective, and cluttering up the rest of the interface.