flatlander_48

In the low and mid-range, but probably less so at the high end, manufacturers are trying to hit a Price Point. It's not skimping for the sake of skimping. Just guessing, but suppose your price target was $1400. If a straight Shimano 105 drivetrain put you over, what you might see is a mixture of 105 and Tiagra or 105 and FSA parts. So it could turn out to be something like 105 shifters and rear derailleur, Tiagra front derailleur and an FSA crank and cassette. It's all servicable, but it has the 105 for a bit of pizzaz and recognition and the other parts to help keep the price down.

My first road bike (listed at the left) was pretty much untouched except I upgraded the tires when I sliced up one of the originals. My second, and current, road bike started with a frame and fork and was originally built up with 10sp Centaur hardware. At the time, fully built up BreakAways were sold with 9sp Ultegra hardware, but that seemed to be going backwards.