The reason is probably that noone active on this forum, privately owns a DS4000E model. Actually, at 20% price difference to the DS4014 it doesn't make any sense to buy the "E" model, considering the certain option to "improve" the DS4014 to the full DS4054 capabilities. I guess when spending this amount of money privately, there are few people who want to be guinea pigs. Moreover, in comparison to other oscilloscope manufacturer's offers, the Rigol DS4000 series doesn't appear as attractive anymore as it may have three or four years ago.
Cheers,
Thomas