I never do microtransactions. The only time I do download add-ons is either when they're free, or when it's a legitimate expansion like Shivering Isles was to Oblivion.
Ive done microtransactions. In an MMO, it can be much more time saving to buy a piece you need to finish a quest for $5 instead of spending countless hours trying to farm it only for it to never drop.
Ive also done add-ons. I bought all the DLC for Amalur and enjoyed every moment of it. Also bought a crystal pack for Child of light which wouldnt have changed much either way by the time the game was over. I did purchase the additional level for Costume quest. It was cheap and fun so it wasnt too bad.