Haha yeah, sounds familiar. That's actually one of the primary reasons to raise them! Unfortunately, your biggest support costs will be from unreasonable people on the cheapest plans. So by raising prices you often weed out the people who complain, but make up for it in the extra dollars from all the silent people who love the product.

The "exclusive features" thing is awesome in theory, but unlikely to matter to most customers. Having a simple, well-designed, straight-forward product can be worth a few extra bucks. Extra features will be gravy in the future (or more stuff for the higher plans).

Free plans are tough, because adding one without a good strategy usually ends up being a distraction and more server/support/etc cost than good for upgrades. Most people will just sign up for a paid plan or a free plan and stay there, unless you have a really great strategy for getting them to upgrade. With that said, I worked at Twilio and we made sure to give a bunch of free credit because we knew getting devs to try it for fun or personal projects would often translate to them convincing their employer to use us for something that made us a lot of money. The difference here is that the true customer was businesses that paid a lot of money.

(If you can't tell, I really enjoy this stuff haha. Hope it's not annoying.)