The Kid-Size league has been a great invitation card for new groups to enter the RoboCup. Low budgeted teams uses this category to evidence their institutions in the field of robotics and helps to raise investments, enabling them to improve their robots for participating in the leagues with taller robots.
However, the Kid-Size league can also cause teams to become accommodated in this cheaper and, somewhat, easier league.
Thus, I believe it would be good to turn the Kid-Size league into a Drop-in league only, with restrictions of size and the requirement of listening to the game controller.
The main idea is to reduce the prestige of the Kid-Size league, making it more like an Entry Category, or even a Base Category, in which the teams could compete in order to foment the investments in their teams. Also, this may cause the teams to interact with each other and develop their robots.
As the teams grows they will migrate to higher categories.
While budget is always a critical issue for the humanoid league, KidSize is currently the humanoid league which is closest to achieving teamplay and, from my point of view. Moving to drop-in only would kill in the egg any chance of producing teamplay. Moreover, this would not solve anything because team who built/bought kid-size robots would have to build larger robots additionally to their kid-size robots, therefore, it will even increase the cost.
An option which is already available this year for team with tight budget constraints is to apply as a joint team, thus reducing the number of robots to be build. And, currently, teams can already apply to the league with a single robot even if this is a strong disadvantage.
For the future, it is likely that there will be a division A/division B scheme in Kid Size. This could help to reduce the number of robots required to reach satisfying performances without requiring 4 robots.
Another option which can be discussed is to start the competition by several round of drop-in games which would serve as a basis to create joint teams when required for the rest of the competition.