Throw in real widescreen (no not stretchscreen, REAL widescreen) and support for both soundtracks and SEGA TAKE ALL MY MONEY.
But who are we kidding? Will just be another Vintage Collection/Backbone port. At least peeps who don't use emulators/bought Gems Collection/have the original SEGA CD copy/owned the PC port will get to play it.
Personally the only filter I like in Fusion is the CVBS blur -- which is absolutely wonderful for games like Ristar.
Such a filter is also necessary - the genesis is built for CRT screens, and the imperfections of RF modulation or component input. Simply put, the sega genesis image is wrong on a modern TV. It literally doesn't work.
I've been playing my Genesis and Sega CD all week on this big-ass CRT tv I finally hooked up, and you'd be shocked at how convincing the transparency effects caused by stipple shading are. Simply put, it LOOKS transparent. Stipple shading, with a CRT TV, essentially let the Sega Genesis do transparency. Such effects, as well as the smoothness of gradients, are flat out broken with a modern tv. The genesis used a lot of neat tricks that modern tvs can't replicate. The result is an ugly mess - look at something like Earthworm Jim. The game is absolutely full of wicked transparency effects, which, when viewed on a CRT TV, actually work and look unbelievable for the hardware. On a modern tv, however, it looks like a harsh mesh of blocks which is far less impressive.
The filter you listed above actually fixes all these effects, and lets modern monitors and tvs view genesis games CORRECTLY, without blurring the screen. There is another filter which is slightly more accurate, in that it attempts to simulate the rainbow banding you got from old CRT tvs when you used stipple transparency, but it doesn't look right (the tint of the transparency changes between red, blue, and green as you move, where as on real hardware you get static bands of rainbows within the transparency at all times).
tl;dr: If you don't use this filter, sega genesis games don't work correctly visually.
Of course, another solution is to just flat out replace the mesh effects with true blending.
SSF, the full speed sega saturn emulator, does this. I agree this is the best solution.