If you can do server side great: do it. The difficulty is accurately predicting how much JavaScript you'll end up writing. If your client-side JavaScript is comparable in complexity to your SSR you'll eventually end up with the worst of both worlds.
If a client tells me what they want built, I bet I'd be able to roughly guess how much js there's going to be, probably within a few hundred lines for a, say, 3 month project.
The larger the project, the large the margin of error, but still, it's really not that hard for the vast majority of work we do. Or at least I do, e-commerce, enterprise apps, etc.