We may need 2Mb blocks, but it's not urgent, and it may be that in the future we need 4Mb or more.
Most blocks are half empty,
This is false. Here's a chart: https://blockchain.info/charts/avg-block-size (.5 is "half full")
The urgency is pretty obvious: we knew that the number of transactions was growing, infighting about blocksize started over a year ago, and the blocks are hitting the limit, and... And here ya are, and it's a beautiful day. Well. I just don't understand it.
Block size is already variable, meaning that blocks with max_block_size of 1MB aren't all 1MB -- that's just the maximum size. In other words, we're not growing the blockchain by 1MB every ten minutes, regardless of the number of transactions.
SegWit won't make the storage more efficient -- it will simply separate it into two warehouses. The amount of stuff to store will be the same.
Like the 2MB blocks, SegWit isn't a permanent solution, it merely kicks the can down the road. In other words, when we hit 1.7 to 2MB blocks, we'll still need a hard fork.