If I'm not mistaken, at the wav presets era of DimPro, Rapture could open/understand his programs (or just use DimPro wav forms in Rapture). And it was a nice addition for users. That's what I mean.
Also, to date, HDD size \ price negates the benefits of compression, and in this case - a loss of format flexibility.
More, for me this product is useful to their content, not just through the use with DimPro. As a result, in this case (compression) more of an inconvenience than the pros.
So, addition FLAC format to Rapture in some way compensates this.
(I'm sorry, I use translator, I hope clearly expressed.)