Twitter requires custom creatives - this is a huge cost. Every TV network can run standard 30s slot.

Average American spends 4h on TV every single day. Twitter has nothing on that.

Actually the worst part of twitter is that things disappear so quickly (till recently). 320MM MAU doesn't mean everyone sees that. A TV ad can 1) be sent to any station, 2) has a good chance of being seen by a large % of people tuned into that station at that particular time.

Yes. You can't deploy the same ad on FB and Twitter and Pinterest the way you can do a TV spot and deploy it on any channel large or small.