Microprocessors vendors started the trend. The microcontroller guys went next. Now it's obvious that the programmable logic guys are falling right in line. The path that I'm referring to is being "market driven" as opposed to "product driven."
At the end of the day, it comes down to who has the best product (and "best" can be described in lots of ways). But by using market segments to differentiate your programmable logic products, it helps board or system designers get their products to market more quickly.
For example, if your programmable device is aimed at telecomm applications, you can make sure that the appropriate peripheral mix is available and write the best drivers for that application. If you're suited for logic within a consumer electronics system, different peripheral attachments make more sense, with an eye toward small size and low power.
Initially, the programmable logic device may have been the same, but by the time it's "application configured," it's closer to a plug-and-play solution for the designer.