Yeah, I use sentries a lot as a commander. It's important to keep Skulks off your power, which can shut down entire bases and lead to an unprecedented disaster from which you can't recover.
In fact, people often pony when you rush sentries early (like before phase gates, which I've done before), but what they don't realize is that the longer you wait to get sentries, the less useful they are. Once the Aliens get bile bomb, they're just food.
I used to think that the Commander was the most important role in the game, but after playing more I've changed my mind. For both the Aliens and the Marines, it doesn't matter how good your Commander is if your team sucks. I've seen a single marine take out 3 skulks or even an Onos by himself. This kind of skill isn't generally expected out of a marine, but it should be. If the Alien players have that much of a skill gap over you, you're going to lose.