In order for Bitcoin to succeed, blocks must be full.
If blocks are never full, then there is never a reason for a transaction to pay more 1 satoshi in fees. As the subsidy is reduced, fees become more important. So at some point, full blocks will be necessary in order to ensure that the revenue is high enough to discourage a 51% attack.
Changes that attempt to prevent full blocks would directly impact the security of Bitcoin.
This needs to be reposted more often:
Full blocks sounds like a naive way to solve the scalability issue but it directly harms the fee economy for the reasons mentioned. Now when spam enters the network, block space and thus fees, and eventually the overall Bitcoin price becomes a premium.
Same argument goes for increasing the rate at which transactions are processed - it would bring the fee wipeout problem with it too, only with more blocks.