My iPhone and (especially) iPad has a ton of MIDI apps on it. If I sell my iPad, and don't wipe it first (but, say, merely delete personal data and change my passwords so the new user cannot access my accounts), I suppose that user could keep using my apps. (Leaving aside the legal aspect.) And that would be true (and actually, less complicated) if you were to sell your Roland with the expansions you loaded into it as well. But in either case, you're not transferring the license, and the new user's access to those things on an on-going basis is not assured. So I agree with Foksadure's analogy, it's similar to your iPhone/iPad/Android... you can sell the hardware, but you can't transfer the licenses for your downloaded apps to the new user. (You even list ikmultimedia as an example, but while they have a transfer policy for PC/Mac, there is no transfer policy for the iOS version.)
But to get back to this particular situation, you're talking about buying the expansions for Roland hardware. But looking at the bigger picture, it's true, If you buy a Lifetime Key for an expansion in Roland Cloud even to use it on your computer (i.e. Zenology), it is still not transferrable to another user, even by paying a fee, and there are many companies who do permit such transfers. Though as Lazerlike42 said in his April 3 comment, there are also lots of VST manufacturers who do not support transfers, Roland is far from unique here.
As for the hardware aspect, though, I'm not sure how Roland compares with other brands. Korg had lots of paid expansions for Kronos... I don't know whether or not they were transferrable if you sold the Kronos (such that the new owner could re-download them if need be, or buy new expansions and have them added to the existing ones). Maybe someone else here knows?