There are a total of 17 ARR maps that qualify for 2-star speed. At 250 Allied Seals, this equates to 4250 total required Allied Seals. The daily Hunt Bills produce a total of (3 * 8) + (2 * 20) = 64 Seals / day, with a weekly Bill giving 100 Seals, for 548 weekly Seals. At this rate, it will take over 7 weeks to acquire 2-star Mount Speed across ARR.

On the other hand, there are only 6 Heavensward maps qualifying for 2-star speed, at a total cost of 1500 Centurio Seals. You can earn a total of (3 * 5) + (4 * 5) + (15 * 5) = 110 Seals / day, with a weekly bill giving 100 Seals, for 870 weekly Seals. At this rate, it will take under 2 weeks to acquire 2-star Mount Speed across Heavensward. I'm not even counting the additional Centurio Seals available from Kugane's Mark Bills.

To top it all off, (Veteran) Clan Marks for Heavensward / Stormblood give significant XP bonuses, whereas those for ARR do not.

All this to say: I think the ARR requirements are a bit high. Considering the number of maps, I think the price for each should be dropped to roughly 100 Seals per map to bring it into line with Heavensward. Note that I do not advocate raising the cost of Heavensward's maps to be in line with ARR.