I don't think it matters much that you didn't start the projects, you are the one who is responsible for them now. That is the part that counts.
If the project improves by making a difficult change then that is still your choice to make. Sure some people will complain, but there is always someone that complains when things change.
Yes, I think this might be a better model, indeed.
But I did not start either of those projects, I came on board later; and those models are difficult to back-fit into an existing project.