Raising limitations isn't really what I'm looking for, then you'll just have a ton of transactions that you have to data-mine. And paid block explorer APIs can fetch addresses with several transactions without problems.
1. Average block time within last X blocks (such as 36, 144 or 2016).
2. Total transaction size on mempool.
Yeah this is exactly what I mean. Normal users who just want to send and receive money don't need any of the more advanced queries that power users and businesses could use for building services on top of them.