We've had this debate many times already. This is beating a dead horse and offtopic to this thread.
If you want and AUR helper, you have a couple of them in the repos. Nobody is stopping you.
But one thing is to try and be "user friendly" and other to bloat the install with things that not all users need. Not all users need the AUR. More than that, you can use the AUR without a helper. Even one could make the argument that the proper way to use the AUR is precisely without a helper.
So I disagree in that regard, I don't think Manjaro should come with a helper by default, even though I use them myself. Because in that case, many users would dare to use the AUR without even informing themselves about what they are really doing, thinking it is just another repo.
And then a debacle like the recent with the glibc update occurs and the ■■■■■■■■■ breaks. Or worse, that recent infected package that tried to spy on users. You have to take a compromise between user-friendliness and user-riskiness.
I still think that a visible link to the proper wiki article in the manjaro-hello should be more than enough: