I think there are enough low tier maps for people to make a progression from those up to the higher tier maps, just speaking from personal experience. I think saying that no one is making low tier maps is quite dishonest. These are rough numbers for soldier maps:
T2: 23
T3: 92
T4: 127
T5: 83
T6: 32
This doesn't include courses on maps that are lower tiered, so the numbers are skewed towards the highest tier of that map. It also includes demo maps, where the spread is mostly t4-6 for those.
I think most consistent jumpers would be able to complete at least T3, so there are definitely lots of options for those people.
The only real gap is T2, which seems very difficult to create interesting jumps for.
People are leaning towards harder maps because it is easier to be creative without the barrier of a low tier.