So raising the limit slowly will stop the blockchain spammers? That makes no sense. If they can spam at 2MB then they can spam at 1MB and at 20MB. We can find measures to live with the spam, but limiting the block size at 1MB isn't a valid solution for this.
Correct. Let's say the block limit becomes 20MB and some spammer was capable of filling up three of them in a row, delaying confirmations for 1/2 an hour. In which case, the same spammer could
right now, fill up 60 blocks at 1MB, and delay confirmations for 10 hours! Worse, once the 1MB blocks are normally 75% full, any spammer with that capability could probably cripple tx confirmations for a whole week!