If programmers had to accommodate the "old" everything, can you imagine how bloated software would be? Yeah, some people prefer 80's clothing, but most B&M retailers don't stock it these days... I'm not dinging preferences, I'm dinging the consequences of expecting preferences to always be honored in the name of "diversity" or "we all can like different music" analogies.
Again, as a programmer, I have to disagree with this statement. Look around at different apps that have skins and the sizes of the skins are quite small. Thinking back to my last involvement with Linux, the window managers provided vastly different interfaces to the OS and were all quite small in comparison to the rest of the OS.
If they had to keep all the old functionality, then sure. But I don't think you'll find many people wanting to keep the old crappy search engine along with the new fast search engine. What they want is a familiar interface to the new functionality. True, they may miss out on a whiz-bang option the new functionality exposes, but that can always be tucked away nicely on an "Advanced" dialog if they ever cared to use it. And most people wanting the old look would say they don't care.