If size and cost are a concern then that ship has already sailed. Current pattern designs are big and expensive, but pattern has moved in the same direction since the inception of the FAI F3A world championships in 1960: bigger and more expensive.
Biggish, yes, expensive, if you want it to be. Personally I just don't buy the whole "pattern has gone so big and expensive it is putting people off" argument. You only have to look at the people with large scale, expensive IMAC petrol jobs in the UK alone to see that just isn't the case.
There's an old auto racing axiom: speed costs, how fast can you afford to go? Paraphrasing for pattern: accuracy costs, how precise can you afford to fly? The best pilots in the world are simply striving to find the best 'tools' to help them achieve victory. There is still no substitute for effective practice.
Your last sentence sums it up. Plus an expensive model doesn't necessarily mean more points, far from it. Look how far CPLR got on a shoe string - pretty god dam far. And his models are still pretty modest today compared to some. Home made wings/tail/rudder, composite fuz yes but hardly costing a gazillion pounds and regular YS etc etc.
If the FAI really wanted to curtail costs then they would have to introduce measures such as:
1) minimum weight
2) raise the max weight to allow the cheaper slighter heavier kits to be viable + petrol engines
3) fuel restrictions perhaps as they do in pylon?
Personally I think F3A planes aren't too bad as they are size wise etc (2m is quite big enough). Just the rules need tweaked slightly to allow it easier to make the weight limit with an el cheapo model.