Looking at readline-ncurses-termcap stack, simplicity and interoperability are not the first words that come to mind. And despite all the work sunk into it, I still seem to stumble upon more or less broken terminals way too often, ranging from cosmetic errors to completely unusable (e.g. bash with broken line wrapping leading to misplaced cursors and unable to see what I'm actually going to run..).
The model is extremely simple. What you experience is just that the terminal state is not coupled to process lifetimes. But this separation is required for interoperability. "reset"/"tput reset" are your friends.
Btw. if you have other bugs than just those from left-over state from crashed processes, try xterm. There are too many other terminals that probably try to do too much that cannot work in all cases.
