Doesn't necessarily matter. Usually the easiest path to resolving the next change request will be taken, i.e. patching on to the existing crappy thing from the 90s. The only thing that can change it is someone shouting. I suspect most software (not the glitzy things on HN) are driven by shouting. Shouting Driven Development. If the customer doesn't care enough about UI to raise their voice, then UI won't be prioritized.