Switch to narrower rims on a hybrid?
I would think that concerning the rim there must have been a misunderstanding. You should be able to run a narrower rim, and simply adjust the brakes, unless there is a reach issue with the brakes.

It's possible that the hubs on your wheels are MTB style, which have a different width than road hubs. You would still have the option of buying new rims and having them laced to your existing hubs if you are serious about running narrower tires.

That said - as a long time recreational rider/commuter - I don't see much benefit from running any tires narrower than 28-25 unless you are planning on racing (which isn't really a target use for your bike).