Interview, yes absolutely -- I've interviewed including a tour of the department. This has been true several times. Thinking about it... I'm pretty sure I'd decline if I saw any less!
Remember, you are interviewing the company, as much as they are interviewing you.
You must forget the advice that you may have been told in school, that you need to find and land a job, period. That's good advice for the school only: it lets them post good graduate placement figures. (My school had such a process, at least; YMMV.) Find any job, when you need money, certainly; but for your career, you can't be living in madness all the time!
Regarding level of enthusiasm, that's very normal. If that was a less technical department, maybe, service technicians rather than engineers, that sounds about right. If it was design engineers, I would be worried. Worried, I think more for the amount of work I'd about to be thrust into, or the amount of chronic-falling-over-syndrome the organization has, or is going to have...
The 90-10 rule applies, as it does to all populations. 90% are casual, "in it for the money" or "it's a job" sort of thing, and squeaked by in school. (The Peter Principle also applies: anyone more qualified, would've been promoted to a role where they are poorly qualified.) The 10% are technically proficient, if not particularly fast or reliable at it, say; but they'll get there in the end. It applies again, recursively: 10% of the 10% are adept, efficient and capable; and 10% of them are the leaders in their field.
Personally, I've met few engineers as enthusiastic as myself. They are out there! Although a lot of this seems to be more a thing of the past, many of them being old, retired, or passing away. (Indeed, this was borne true in school, when I asked to test out of more subjects -- the dept head said they used to be able to do that, but changed the policy in recent decade(s) because it wasn't helpful. As a result, I had to take several entry-level EE courses...
)
But at least there are a few here.
Tim