Thinking About Stats

Most RPGs use stats. They're usually the first thing you do when creating a character and so common that you don't even think about it. When I stop and consider the role stats play in the fabric of an RPG it breaks down to three main things:

Stats are important as benchmarks.
Stats connect a character to the game's world by providing a context for how their skills and abilities fit into that world. RPGs are about having fun while interacting with a fictional world, and stats are the reference point that helps you determine what shape that interaction takes. They guide how your character might face a problem, what sort of solution they would come up with, and how well it would work.

Stats should be random.
Rolling for your character's stats creates challenges for them and sets them up to develop through play. If you wanted to play a wizard but rolled a low INT you have a choice: Reroll your stats until you get a set of numbers you like, or use the low INT and run with it. Be a sadsack wizard who's questing to become more powerful and focus on raising that stat throughout the game. Those decisions can't really come up if you use a non-random method like point buy to generate your stats. Randomness creates more interesting options to play with.

Higher stats aren't better.
Most folks assume players will choose higher stats for their characters if given the opportunity and that higher equals better, but high stats can be boring. Taking risks is part of playing games and where's the risk when you know your rolls will succeed because of your good stats? It's usually more fun to have a solidly mediocre statline and let RP carry the game, abysmally low stats the require extreme cleverness, or a wildly inconsistent assortment of high and low than it is to have high stats across the board.