Sadly you're probably right. The cost of buying them - and upgrading free to about level 5 or 6 - is no big deal to me but it's evident that Gree are doing this because of the (relatively small number of) players who've got into a habit of finishing all their big payers with gold in order to make doing the next LTB easier. Gree still want them to have to buy game cash though, so in order to make that happen everybody else has to lump it.
This game gets more like real life. Rich people move in; property costs shoot up; those on the lowest rungs aren't affected because they don't even try to enter the market, but those in the middle get squeezed!