I'd have to agree with you. We've been on many many cruises in various parts of the world. We have always thought of cruising as an affordable overview of many places at once. On most cruises we end up really liking a port and wish we had more time. We have gone back to many on land vacations.
The first time we did this was going to Catalina Island for a land vacation after cruising there on the old Viking Serenade in the early 90's. Since then we have followed up cruises with land trips to Costa Rica, Norway, Belize, Roatan, Portugal, Grand Cayman and Cozumel. As someone else said, when the cruise ships leave the places become very different. We have noticed that the people actually are nicer when they know you aren't on a cruise ship.
In Catalina the people were openly disdainful of the cruise crowd once they left. In other port cities the change is subtle but noticeable.
I don't think there is a "best" way to travel. If you like to submerse yourself in the culture and feel like you know the place, a cruise isn't going to do it. If you simply want an overview of the world at an affordable price, a cruise is probably the best way to go.
We like both for different reasons.