Dead end means that reinstalling requires floppy wich has a workbench.library. If there isn't one how to get one?
While I haven't checked, I would assume that Cloanto would be happy to sell you one, i.e. a disk including the workbench. Thus, I don't quite see where your problem is.
Another point is, is even possible to have all filesystems in official rom? like FFS, SFS and PFS? Latter two are now free, but selling them might be impossible?
The FFS is surely ROM-able, and at least the 40.x version is licensed by Cloanto, including a full source code license as I came into learning. I would hope that they have obtained all necessary rights on the updated version they provide, though I do not know how it was created - but that's at least their problem and not mine. I hope their lawyers checked...
The V45 version was done by Heinz for 3.9, and while I do not know his contracts, I would assume that it is still his source and it was only licensed to H&P. So whether this could be put into ROM from a legal perspective, or whether Heinz would be willing to provide his source for such an activity I do not know.
As far as the SFS and PFS is concerned, I neither know. I do not know whether it is technically possible (i.e. is the code ROM-able) and under which license they are available (so, what level of "free" your "free" actually means). I was never interested much in either of them, so I did not check.
Anyhow, any RDB-aware host adapter will be able to load a filing system from harddisk, so there is really not much trouble using an alternative or newer filing system even without the ROM given there is a suitably simple installation process for the filing system. From a technical perspective, it is entirely unnecessary to put the FFS, the SFS or the PFS into ROM.
One thing that irritates me is that you're so much playing with the "ease of installation" argument, leaving aside that is much harder to actually *prepare* a custom ROM in first place than to install an Amiga from its native ROMs using software updates. Unless you imply that "somehow" the user willing to make an installation gets his "custom ROM image for simple installation" from "somewhere".
That, however, is quite clearly piracy, without any argument, my friend!