Other than the myriad of plot contrivances in Star Wars films the will of the Force doesn’t have any bearing on how one uses it.
Would it be safer not to dabble in Dark Side teachings and training? Sure, but the advantages one could be blessed with if they find balance is inconceivable. That alone should warrant someone like Luke to at least try. There are so many things that have been invented and events that have transpired because someone took a risk and didn’t give in to fear and apathy.
Perhaps worshiping Ashla alone doesn’t mean to abandon all emotions but the first line of the Jedi Code says this and it’s canon. This would be a good way to retcon that shit.
Either way you look at it when the Jedi intervene they are using The Force to reach a conclusion through Forceful means which means they controlling fate.
You don’t need to have people use their base emotional states (anger in this case) to not fall to the Dark Side. All that Luke needs to teach people is some self control, the possible fates for those who veer too much to either side and above all that one can’t become a whole person or even a person who is truly knowledgeable unless they truly embrace being open minded and adapting when need be. Of course this would be in addition to a great deal of standard Jedi teachings.
The quicker and easier aspects of The Dark Side would be quite advantageous for Luke to adopt into his new philosophy. Sure, it’s not inherently stronger but using it to gain power quicker is a definite advantage for those who are still training or trying to progress themselves extensively.
This all comes down to whether the dark side can be controlled. To me, a fundamental aspect of the nature of the Dark side is that it can’t. That’s why it’s so dangerous, and why the Jedi avoided going down the path in the first place (even if they went overboard).
It really feels like you’re stripping it of its teeth if somebody can control it, even if it takes far more training than not using it.
(As for the Force having its own will: There’s a lot of hints that it does. From Star Wars where Obi Wan says that the Force partially controls your actions, to Rogue One where Chirrut merely trusting of the Force lets him complete his objective)