It's a win - win for most bigger channels, Fans get Shirts and show support, and creators get more revenue. Channels like Phillip Defranco create merch on like a weekly basis for their fan base so you really can tell when a creator cares for their fans. It's not about self-importance its just about having a business strategy. Some people i'll admit do it as a trend, but others really know what they are doing. It's hard to make a living off YouTube Revenue. lol most people don't pull PewdiePie numbers.