>>1168476>Why do cheaper bikes use 21 speed gearsA 7-speed cassette and derailor require less precision from the manufacturer and tooling already paid itself off, therefore they are dirt cheap.
I could get a 7 speed 11-28 cassette for about 10€ and a rear mech for about 15-20€ on the internet for that reason.
10-12 speed cassettes are significantly larger and the mech needs to be more precise to shift properly on those, also they are still pretty new, therefore manufacturing is more complicated and the tooling did not pay itself off so far.
The prices for these are much higher for that reason.
My issue with 1x systems is that they require realy large cassettes and usually have tiny sprockets for the final gear, meaning that you have to use relatively small cogs on the way to the trail, wich leads to additional wear.
To add on that they increase unsprung mass on the rear wheel and have less range or larger steps than a 2x drivetrain.
The good thing is: you can convert most 1x drivetrains into 2x or even 3x drivetrains for little money, as long as your frame supports a front mech.
For me 2x is the best of both worlds.
>no fiddling for middle ring, just 2 adjustment skrews and getting the cable adjusted somewhat>extra range>not requiring latest 11 or 12 speed equipment>lighter cassette>easier adjustment of rear mech due to higher tolerances 
