There SHOULD be new collector levels!!!!
I do agree that there should be an incentive to LVL up collectors cause i always find ones that arent maxxed and its just upsetting. They are the only way NEW loot comes into the game and some ppl feel they dont need to max them.
As for new levels, im sorry but i DONT agree with the OP, they do need to add new LVL's.
When this game was designed TH8 was the max and LVL10 collectors were the MAX. None of the loot percentages were really designed with HIGHER TH's in mind which is why we recently saw such a large change in loot due to this reason.
When TH9 came out, they added a new LVL to collectors and made it available to anyone TH8+ (TH8 AND TH9 at that time) and when th10 came out they gave them one more collector which shows that they know that this is the only way for NEW loot to really come into the game and needs to be scaled as the game scales.
With all the new upgrades that have come out as of late (TH10, new defense levels, new walls) we need an increase in the way NEW loot comes into the game. The latest change adjusted the way loot moves around which helps but we need more loot in the system.
This can be done in 2 ways
1: Across the board resource production changes - Make all collectors increase production by x%
2: Create new Collector Levels
I would like to see changes to BOTH but would be happy with at-least new lvls for TH9+
TH8 needs no other help so dont be greedy and ask for it as thats not fair.