Is BootMii useless if I can't use it as a boot2 replacement?

Is BootMii useless if I can't use it as a boot2 replacment? If so, should I uninstall it?

Not entirely useless, but most of it is. You can still backup your NAND, you just can't recover it. Could be useful in a semi-brick, or (alongside Priiloader) could solve a banner brick, if you are not certain what was the title that caused the brick. Maybe it isn't the best sollution, since it will make your nand data go all the way back to the day you made the backup. Unless you make backups of your NAND periodically, there may be quite a loss of save data or upgrades in this process. In a uttermost scenario, maybe a hardware sollution for bricks might come and a NAND backup should prove useful.

Anyway, for your case, Priiloader alone gives a little help, but Bootmii/IOS itself does not get in the way, so you could install it as well. You won't be protected from all types of bricks though. Be careful when you are modifying the NAND, so you won't do anything irresponsible.

BootMii/IOS exists mainly as a front end for MINI on Wii's which cannot have a modified boot2. As there are only a few MINI apps right now, it is practically useless. However, if you want to run Wii Linux with WiFi, then it has a use. And in theory it should eventually allow some uber awesome homebrew to run, without the limitations imposed by IOS and its security (e.g. in theory I believe you could install fakesigned content from MINI without needing to use any IOS exploit, although you would need BootMii to be installed for this), and with raw, unfettered access to the hardware, which could bring some interesting developments.

As it stands, right now its not that useful, but as more people develop apps for MINI, it will become very useful.

It doesn't help that people seem to like to use it for piracy tools.

Thanks, guys. I'll keep BootMii installed for the moment.

Asking something related, I tried to check booting homebrew from mini, as SifJar told. As I suspected, Bootmii doesn't boot any application from mini even with a fully working system menu. Are there mini versions for apps like Dop-Mii or AnyTitle Deleter?

Nope. Those apps rely on IOS and the features IOS provides. MINI Is Not IOS (that's what MINI stands for), and therefore doesn't have the same features and functions available. Apps must be written from scratch, or at least highly modified to work with MINI, hence there are very few MINI apps available right now. There is a MINI SDK which must be used to develop apps for use in MINI.