Recent Thunderbolt displays at least ship with the adaptor in the box. If you’re going to be compatible with both and you’ve already engineered a Magsafe 1 connector and a Magsafe 2 adaptor that’s a reasonable compromise.
Eh. If you're manufacturing units now (which they are - my TB Display has a March 2014 date of manufacture, perhaps the "reasonable compromise" should be to ship with the connector that has been standard for over two years now and an adapter for the old standard.
