It sounds like Denim & Co just isn't your style. I can't figure out why someone would start a thread under "My Favorite Brand" and post why she doesn't like it.
I challenge you to go to the department stores and find these styles and look at the workmanship. I never find a loose button or threads hanging from seams on any D&C item I buy (and I have a closetful). The workmanship is head-and-shoulders above what you get in a nice department store.
As for style, I would not call D&C frumpy. Personally I love D&C. And I have noticed the price has gone up. But so has the price of everything (but it would be plitical talk to go into why). I have never found a brick and mortar store to have as nice of clothes especially in such a variety and made so well.
Most important to me is that they fit me, a mature woman. I find the sizing consistent. The actual measurements are linked on the online description too. I wear an XL and I'm petite. It's very difficult to find nice clothes locally. I buy D&C almost exclusively.
I'm sorry you don't like it. Clearly it's not your "favorite brand."