is the improvement you're talking about going to be built into the blockchain?
I don't know, if it will be there. I know it is technically possible to do so. But along the road, there could be many different proposals, and I don't know upfront, which technical solution will win, and will be merged.
In other words, will my grandmother not have to undergo any technical process to manage her transactions with someone else?
It is always "blockchain first, clients second". Which means, that for example here and now, you can use different sighashes than SIGHASH_ALL. You can for example sign only the first input, and the first output, if you really want, and then move that signature to a different transaction, without invalidating it. But: having something supported on a protocol level is one thing, and having it supported by the client is another thing.
There are many things out there, which are possible, but are not yet supported by the clients, and they have to be implemented first. For example, K-of-N multisig on Taproot would be nice to have.
Will she need to calculate anything, or else her transaction will be stuck?
I don't think so, because if you for example sign your transaction, you just click "Sign" button, instead of computing SHA-256 of your data manually.
So, anything that requires additional steps to perform a simple transaction is most likely going to fail.
Of course, but getting to the working solution is a long process: first, you have some discussions, then you write a proposal, then it is discussed, when it comes to all of the details, and then there is a BIP. Later, there is some code to be merged, and it is discussed even further. And if that code is a no-fork, it can be just merged. If it is a soft-fork, then you have to reach consensus, which is hard. And if it is a hard-fork, then you need a very good justification, like "all old clients will stop working without that change in 2106".
But here, in this subforum, we are in a "Development & Technical Discussion" board. Which means, that I assume (and that assumption may be wrong), that people are somewhat familiar with the code, and how it works. And they usually are, because if they are not, then more general topics can be created in other boards, where you have discussions on a more general level. But: if you want to change something, then you have to touch the details, sooner or later, because "the devil is in the details", and for example I could accept Ordinals, if they would be implemented as a commitments, where each TapScript would start with OP_RETURN, to prevent those data from being pushed on-chain (or better, where such commitment would be hidden behind a signature, to be compatible with all existing address types, and not only with Taproot).
Edit:
BTC is pretty complicated for the average person in its current state.
If something is too complicated, it can be automated. And it can be more user-friendly, but it would require some effort to get there. And the biggest challenge is to find some programmer, who will want to do so. Because you know, for many developers, things are obvious. They start with zero knowledge, and when they start, this is the time, when they know, how to improve things. And then, they learn more, more, and more. And then, they know enough, to use it properly. And sometimes, they no longer feel the need to improve things to be even more user-friendly, because they just learned, how to handle all of that stuff. Which also means, that there is a huge potential for user-friendly wallets, and I think that market is not yet fully taken, and there is a lot of room for many improvements.
Also, I agree that BTC is more developer-friendly, than user-friendly. Technical construction of Bitcoin is what bring me there, because it is something, that you cannot see in a typical software, which was written before. But it is probably a good take for another topic, if it is not already created in some General Discussion board.