It's annoying that once software products become extremely popular, the developers/companies often start adding features in an attempt to be everything for everyone. This in turn makes the software unusable, because the developers are too overloaded to properly maintain their once core business. Eventually it gets replaced by a new product, and the cycle repeats itself.
I think it was jwz who said something like "every program expands until it can read email" (I'm sure I'm butchering it).
“Every program attempts to expand until it can read mail. Those programs which cannot so expand are replaced by ones which can." -- Jamie Zawinski