I've kind of shifted in the same direction too. I used to build a custom launcher/theme/background widget setup, now I tend to even keep the stock background because I basically never see it anyway. Same with customising apps. I tend to just learn the defaults and then it works wherever I use it.

That said there are certain customisations which do really impact my productivity, and they tend to be ones which are 'off the beaten path', so I'm very much in favour of keeping software configurable. There are also tools which I spend a lot of effort hammering into a usable state using their options and extension support, and I wish they would take a more 'toolkit and framework' approach (as opposed to thousands of ad-hoc options), and/or present a more useful default.