I only think clothing merchandise is ridiculous when it's very blatantly advertising something. For example, I won a pumpkin carving contest my school hosted last year and won a hoodie... with the Nike logo on one side of the zipper and the school's name on the other. I feel like a walking billboard when I wear it, which is a shame because it's actually very comfortable.
When the advertising is very subtle, like simply a mudokon face on a t-shirt or a paramite "bursting" through the chest, it's nice. If someone sees your shirt and they like it, they could ask, "Hey, what's that from?" and the wearer has the choice whether or not to tell the person it's from a game series you enjoy enough to wear merchandise from.
E: MSPA is a good example of what I mean by subtle. Their shirts look like just shirts with some symbol on it, rather than an advertisement. They're very distinct to people who know what it's from, though. The shirt I own relating to it I've gotten fans of Homestuck approach me to talk about it, and I've gotten people who have never even heard of it approach me to compliment my shirt, then ask me what it's from or where I got it.
An example of their clothing merchandise.
The same can be done for Oddworld.
It's very simple, not in your face advertisement wise, and something I would buy and wear for a reasonable price.