I think it is both unrealistic and unreasonable to demand the same level of security at all times. The resources needed to attack Bitcoin is astronomical at it's current stage, to the point where it is ridiculous to be attacking Bitcoin, and we still have block rewards. I don't see the need for block size to be increasing because there is nothing to be compensated for. Bitcoin is secure enough at the current stage, and it would suffice to have a linear increase for the near future.
transaction count has absolutely no relationship to security
a 500byte block. a 5kb block, a 0.5mb block. a 1.5mb block or even a 4mb block. changes nothing for asics.
they just receive a 256bit hash. and thats what they compute.
the transaction count increase desire is not about security. its about utility.
actually making bitcoin useful
bitcoin in 2014-15 was doing great, thousands of businesses were accepting bitcoin. but now its at a point where hardly any business wants to adopt bitcoin and instead are adopting other altnets