I think it can add a lot of life and expression to just add any random real instruments, (or even various other objects), and that can certainly be an easy and rewarding way to get started. This 2-hour challenge guy, Ben Burnes, has a box of toys, and various instruments he uses - and his cats get sampled every now and then as well.
Well, I have to say some aspects of the bowed strings have turned out to not be as difficult as I expected - and vice versa. Either way, there is a lot that needs to be going on, all at once, in a very controlled manner, before you can get anything remotely musical and expressive out of them, so one should probably expect at least a few years of regular, determined practice to get to the point of actually recording anything with the “typical” tone, vibrato etc one expects from these instruments. Also not sure about cello vs violin; for example, violin vibrato is difficult due to the delicate balance of tension (and mostly lack thereof) and motion, whereas the inital obstacle with the cello is basically having anything much happen at all, unless you have very big and strong fingers. Same with the bow; playing softly on the violin in a controlled manner (especially with vibrato) takes years to learn, while strong, clear notes on the cello is almost equally difficult due to the weight and size of everything, and the extreme tendency to scratch if you don’t get the bowing just right.
But, words cannot describe the satisfaction when you finally start getting it right every once in a while! Worth every moment of frustrating exercises, aching fingers and whatnot, at least to me. Giving up on these instruments is simply not an option for me at this point.
Anyway, there are many other pretty expressive instruments that aren’t nearly as difficult to get started with. Maybe it’s even a better idea to start with those, actually? What I realized here is that, once you get bow, vibrato etc under some level of control, you hit the next problem: What do you actually do with it!? And this applies to ALL forms of expressive playing, even samples with modwheel expression. If you can’t breathe life into sampled strings with the modwheel, you’re certainly not going to do it with the real instruments, or with your voice. I think it’s all basically the same underlying “mechanics,” and what you have to do to actually make it happen is “just” technique.