I dislike games that are split up from day one, for so to be sold in parts. That would be day one DLC.

Other than that, DLC is just a streamlined system for what would earlier be called expansion packs. Except they usually are smaller than expansion packs, and the total cost of buying all of them would be more than an expansion pack but still offer less content than and old school expansion pack would. Blame the market for this, they're the ones throwing their money at it.