I would love to see this happen. Having the ability to level two craft skills to 100 would give me incentive to finish off Woodworking (currently at 79+1), and level another craft to 100 (haven't decided which yet). Moreover, it would probably make me want to level another two craft skills with my mule character.

Low level gear, at least on my server [Valefor], is scarce. I'm in the process of leveling SCH (currently at 25), and the pieces of armor I have been looking for are never in stock on the Auction House. An assumption that is made by a lot of players is that folk level a new job to ~11, get themselves into a "Summoner Burn" party until level 30 and then power through Abyssea until level 90. This assumption is wrong ,and is what I believe to be the reason for this scarcity. There are still plenty of players who level the old-fashioned way (myself included). Therefore there is still a market for low level gear, but there is little to none being produced by crafters. Increasing the extra skill levels from 40 to 80 may partly solve this scarcity of gear.

Something which I believe will compliment this update would be increasing skill up rates. Maybe not a constant increase, but rather, for example, a timed enhancment, obtainable every 24 earth hours, which lasts for, say, 30 earth minutes that will give you at least a guaranteed 0.1 skill up for every synthesis. That's purely a quick example. There would have to be some sort of increase in skill up rates to give non-crafters the incentive to take up crafting (and to give crafters incentive to level a second craft to 100), especially if you [SE] plan on increasing the extra skill levels above 80.

I am certainly looking forward to seeing more update information on this, and also seeing how far it progresses.