As the MSQ hands out HQ ilevel 115 gear for all slots before you hit the first dungeon in HW, you are not seeing 'new players', you are seeing their alts. I can understand why they aren't in i115 gear at that time: there is a single vendor for left-side gear, and they do not have a Buy Gearz Here sign.
To purchase HW gear on the MB can be a half-to-1 million gil expense, as I know from experience.
A better solution than ilevel requirements for all dungeons (really? what should we REQUIRE of a level 15 player in Sastasha?) might be to start dropping ilevel appropriate gear as part of the HW FATEs, which might spur the mob in Northern Thanalan to move on.