Well, this board is to enable the earlier models, for those who like them for various reasons mentioned elsewhere. I for example like 'the Amiga we all had', A500 OCS with 512KB trapdoor fastmem. I'm a coder, so I wouldn't mind a 68020 for assembling faster while still being able to develop for the exact-same-chipset. I'm buying one or two, but not for that since I already have a dev A500 with 68040.
I'm buying the boards as newly made replacement parts instead of fiddling around with sidecar harddisk/ram expansions that may or may not work with various libs and kickstarts. Plop it in and you can transfer anything you want to an A500 in your living room. I'm a demo guy so few A500 demos would work on some later model. Much better than searching for lib version combos that work with kickstart x and SCSI adapter y.
Also, with the A1200 adapter there's at least the hope of getting an A500-060 running. Maybe. That's my other angle
While you could go all internetty and USBey with a clockport-enabled 68020 or higher A500, that's not my aim. It's simply a better solution. Stock A500 (or similar model) (that you already have or can be got cheaply) + 1 board and you have a faster machine with actually more possibilities than an A600+ACA630!
The 68020 does give a good boost over sidecar expansions when it comes to IDE performance though. Some may think this reason enough
As I said, a 1-card 'enabler'. Just like the 4 MB fast+kick socket+IDE board by Tom (see Amibay thread)