I don't think remembering rm is the issue. It's remembering all the options in all their variations. Take the ps command. I tend to use it as "ps aux" - but I have no idea what the a, the u, or the x stand for individually. I know other people who use "ps -ef". (Also note the difference : the aux doesn't require a dash, and if you accidentally put it in, it doesn't do what you want it to do.)
As another example : the -v option. In most tools this means "verbose". In some tools, but not all, you can pass it multiple times to increase the level of verbosity. But then there are a few tools, e.g. top, where -v seems to mean "version" [0]. Or take the -h option. On many tools it stands for "help". But on tools like ls or sort, it stands for "human-readable".
To me personally this is not an issue - I know by heart a few combinations of options that I use frequently, and I know where to find out the details of those, as well as other options I use less frequently. But I can see how it would be easier for people to pick it up if those things were just a little more standardised.