I'm not PAYING for anything. I haven't spent a dime on ME3 microtransactions. I have, however, played plenty on the free maps and unlocked several of the free add-on characters and weapons.
You may not have been interested in it, but if players like Mem, my friends, and myself enjoyed it, then it did add value to the game. And if they created the multiplayer with the intent of sustaining it through microtransactions, they wouldn't have needed to divert funds from the single player part of hte game.
Since when have map packs been free? (and just to be clear, ME3's free multiplayer DLC wasn't just maps, but also new weapons, playable characters, and even a whole new enemy faction (the Collectors)). Halo, Call of Duty, Battlefield, etc., all release their multiplayer DLC and map packs as paid add-ons.
"The Stone Prisoner" was free with any new copy of the game. The explanation given at the time was that the content of The Stone Prisoner would have had to be cut from the game entirely if they hadn't been able to release it as DLC.