I think the main reason people don't comment is because you don't have many opportunities to involve the subs, which is fine given what your channel is. Most comments stem from controversial topics or significantly funny moments in a video. If every person that watched your video commented on what they were thinking, you'd have a bunch of "awwww so cute <3" comments, and some people don't feel the need to do that. So don't be offended or disappointed by that, it's to be expected.
Now, I have to say, you're channel is too damn adorable, haha. I honestly had no idea what a chinchilla even was before these videos, but they look like adorable animals! Now, with channels like this, I worry about people not being able to upload a ton of footage, since you can't exactly make a chinchilla do exciting things, it just kinda does them, but I think you have good content that's consistently put up, which is good. Honestly, I never thought I'd be reviewing a channel of chinchillas, but I think it's a pretty cool idea, and you're been running it pretty damn well so far.
Again, just don't be upset at the lack of comments, you have videos that aren't totally demanding of comments. I think you have good quality videos, and you have a channel that I think all chinchilla lovers will want to be a part of!