In Bitcoin the block size limit was eliminated and replaced with a block weight limit which better reflects the long term operating costs for node. The raw 'size' of transactions inherently is becoming less meaningful in the long term with things like transaction compression and compact encodings.
The weight limit doesn't map perfectly to any size limit because its limiting different things, this evening most blocks have been about 1.3 MB.
If you were traveling at 120 MPH and then accelerated to 156 MPH you would not say that this was a small difference without consequences.
It mattered significantly, in several respects. E.g. https://bitinfocharts.com/comparison/bitcoin-transactionfees...
Increasing supply above demand radically drops fee rates. That is the logical, predicted, and observed behavior-- both in Bitcoin and in other similar systems.
The current fees are well above the marginal transaction costs of processing and storing those transactions. (I estimated it was 3cents/kB, assuming GB scale blocks on ~1000 4U (36 bay) servers with 10Gbps networking distributed world-wide.) Other analysis I have seen erroneously assumes the POW is a marginal cost: which is only true with a tiny, limited, block-size.
During the September 1, 2018 "stress test" on the BCH network, the average transaction cost actually went down. All while the network processed 2 million transactions in a day.