[jiggy2011]

The problem is that interfaces will typically change over time. So really you are talking about maintaining backwards compatibility which means maintaining a bunch of old stuff riddled with technical debt.

If you are designing a new product to a tight deadline, it seems very attractive to leveridge all the features of "the new hotness".

[milfot]

This illustrates the core argument for conservatism (in the burkean sense.. as commented below). You have to move slow to make sure you don't break things that were working (as in.. if it ain't broke). There is no such thing as tight deadlines in conservatism. As with all things, I disagree with applying a rule to unforeseen situations. Sometimes you need to adjust your rule and sometimes you just have to break stuff.