The max block size seems to me to be a very important issue because 1Mb is certainly too small to support a global currency with a significant user base. Even if bitcoin just has a core function as a currency but not an all-singing all-dancing payment system. Like everyone here I would very much like to see bitcoin one day replace the disastrously managed fiat currencies.

My question is: Does increasing the max block size really need to be a hard fork?

Couldn't the block versioning be used as already described below regarding the introduction of version 2?

"As of version 0.7.0, a new block version number has been introduced. The network now uses version 2 blocks, which include the blockheight in the coinbase, to prevent same-generation-hash problems. As soon as a supermajority, defined as 95% of the last 1000 blocks, uses this new block version number, this version will be automatically enforced, rejecting any new block not using version 2."  (source http://blockorigin.pfoe.be/top.php)

Lets say a block size solution is determined such as a variable limit, or a simple increase to a new fixed value. And it is planned for block version 3.

The new software change could be inactive until a supermajority of the last 1000 blocks are version 3. Then the change to the max block size becomes active. The result is close to a "soft fork" with minimum risk and disruption. This would prevent some of worst blockchain forking scenarios described above.