New businesses need to start making revenue immediately and hopefully can afford to implement a script-less version when (and if) the site becomes popular.
Our POS (in operation in a controlled environment) uses AJAX profusely. Re-use is very tempting.
We could develop without script from the ground up (thus eliminating the problem completely), but we feel it limits our potential and usability.
I suppose the morale of this story is to be open to change and experimentation.