I would say that we absolutely don't need so many version tags. I would argue that all we need is ubuntu and then the version can be mentioned in the body of the question. Yes, there are difference between Ubuntu versions but they tend to not be very important. Also, most of them are down to the various pieces of software bundled with the distribution.
For example, networking changes are usually dependent on the kernel and DE changes etc are just about what GUI you happen to have running. Both of these can actually be changed by the user without affecting the version of the OS. For cases where the version really is relevant, it can be mentioned in the question body, no need for a tag.
More practically, having so many tags makes everything more complicated without actually offering any improvement I can see. It makes it much harder for a user to find the tag they want, it makes it more complicated to search, it can give the wrong impression that a shell-based answer that worked in 8.04 won't work today (most of them will), it means we have loads of obsolete tags for very old versions etc.
I suggest we merge all of these into a single ubuntu and use that tag and that tag only going forward.