There's no definitive answer to this (I've asked the devs in the past and they' don't know either) because the original guy that announced Monero, was thankful_for_today and he's no longer around. However, it does seem that the issuance schedule and Monero's does seem to match up so that both reach a total of 21 million coins in the future. This MAY be coincidence, but it's likely because the creator wanted to create a fairly closely matching issuance that was on par with Bitcoin's.

So to reach the same level of disbursement to miners, and since there is a tail emission that significantly slows, it's likely that thankful_for_today or whoever coded up the issuance wanted to make them line up. It may not have been for aesthetic reasons though, it's could've been because they felt the tail emission should kick in sooner and felt that since the XMR will not have a hard limit that the necessity for Monero to hold back coins over a longer period.