Why would you visit Thailand for the first time and skip Bangkok? Would you visit the UK for the first time and skip London? Or France and skip Paris? People telling you to skip it are people who live here or been here multiple times and know what towns they prefer. Much like many Brits don't like living in London or many Italians don't like living in Rome. But for visitors, it's completely different.
You can only extend one time for 30 days. You can exit and re-enter for another 30 days visa exempt entry, and extend it again for another 30 days. If you do this repeatedly, immigration may stop you as you won't seem like a genuine tourist. You can also apply at the Thai consulate in another country for a 60 day tourist visa, which can also be extended once for 30 more days.
if you are in Thailand longer than 3 months, the IDP isn't accepted as you are supposed to get a local license. That's all people are referring to. Valid real IDPs are accepted together with the home country license. IDPs can't be used alone without your home country's license.