It’s important to note, that these things are designed for the average user. If you want to change the wifi password, you are by far not an average user. Most users just plugs in and never even think about that, and the number of that kind of users are several order of magnitude higher than the conscious ones. For them it’s much more secure to set a random pw. If you let them select a password they will choose 12345 or password.
If you know what you are doing usually it’s better to buy your own router where you can change everything the way you like.