Generally, if you take some time and plan your build, and you realistically look at what you're going to get to, then sometimes going up to a better board has advantages with more features and such. Those looking to do a relatively 'normal' gaming system though would perfectly well served by a 'normal' (ie: non-Z97) board.
For example, someone just looking to put together a Haswell build, with a single GPU and knows they're not going to go SLI or Crossfire has absolutely no need for a SLI certified 'gaming' motherboard. Likewise if you're going with a non-K CPU, why go Z97 which is the only sanctioned overclocking board?
That being said, sometimes they bundle everything together and they might not offer certain features with each other. For example, I don't know of many B85 boards which offer x8/x8 SLI or Crossfire in spite of the fact that it could be done quite easily. That seems to only be available on a Z97. Likewise, someone going with a -k CPU can only do overclocking (allegedly) on a Z97, although at least they DO offer Z97s that are not SLI boards.
For the most part your average gamer, going with a non-K, single GPU system would be perfectly well serviced by any motherboard (by a decent manufacturer of course) that has a single x16 PCIe slot and physically fits in their case. They can easily put an i5 or i7 in there, put in a nice fat GPU like a GTX980, toss in a SSD and a multi-TB drive for bulk storage, and have a very potent gaming system. For that, you absolutely have no need of a high end board.
It's when you want to get more complicated that the higher end boards are necessary. They'll offer dual-GPU support (or higher) for SLI setups. Those connections and the PLX switches for enabling even higher GPU count SLI systems cost money. Likewise, so does enabling M.2 PCIe based drives. Meanwhile, those boards are actually physically bigger. More materials cost. All of it winds up adding up in the long run which is why they can easily get into the $200-300 range for a high end gaming motherboard.