I doubt that. Too many other identical threads for this one to become so important.Well this should be fun. Five year thread begins.....now......
+1. Nail on the head. ImoI think improved quality is a valid reason, in addition to reasons such as exclusivity and marketing.
If a company is highly focused on quality, then the more control they have over the manufacturing and design processes, the more easily they can control quality.
Of course this does not mean that all in-house movements are high quality, nor does it mean that an external movement can not be high quality. However in general, in house movements tend to be of higher quality.