What's the point of the MiniMig?

[freqmax]

I think the point is that HDL (vhdl/verilog) files don't break. While physical hardware will.
Some components may be obsoleted, but you can easily find a functional replacement. Try to find a factory made Agnus chip....

All your own Amiga hardware, AND the ones you buy from will have their hardware malfunctioning eventually. The longer time goes the less hardware there is to use as "originals" to model re-implemented HDL driven clones around.
(mains transient, thunderstorms, soda spills, cracks from fall, faulty connection, ESD, thermal cracks, shorts, moisture induced rust, leaky batteries)

Anyone had a dryied out capacitors within the powersupply fry their equipment on startup from not being used for a long time..?

A nice portable DVD player hack would be to replace the mainboard with a Minimig. So one could play anywhere.. :-D
And Amiga hardware is also quite efficient.. (MS-Pocket PC proberbly ain't..)

[freqmax]

There are some possibilities with the Minimig. That may actually make it more sought after.
It's likely possible without any hardware modifications to run Atari ST, Macintosh 68k, Sega, Early x86, Proberbly most 8-bits. With some fpga tricks even early Sun, SGI, NexT aswell.
Then there's the possibility to do demos coded directly in HDL (like vhdl) and really exploit the fpga power. Or even use the fpga capability to interface with other electronics as logic analyzer etc..

[freqmax]

For C64 there is *.tap files that are digitized casette tapes (C2N dassette).

Btw, as the FPGA sits like a gateway between cpu & memory. One should be able to implement MMU in a noncompatible way. And memory protection. Viola modified NetBSD will run :-D