If we already know that the solution is a block increase I don't understand why it should be an increase to 2mb. If the increase is to be to 2mb in 2 years or less the community will be facing the same problem again.
So, in this sense, the increase should be to at least 8mb or even more.
I guess the current line of thinking is just to kick the can down the road. You do not implement something before it was thoroughly tested. I agree with this thinking in the sense that developers need to scale Bitcoin without risking the integrity of the whole network.
For example - "
In 2MB blocks, a 2MB transaction can be constructed that may take over 10 minutes to validate which opens up dangerous denial-of-service attack vectors. Other lines of code would need to be changed to prevent these problems. " - quoted from
https://bitcoin.org/en/bitcoin-core/capacity-increases-faq#roadmapYou cannot just dump bigger block sizes into the protocol and hope nothing goes wrong, because it is a Billion dollar network. Let's just approach this with caution.