Well, this is what you said..."aparantly the "tripod antennas on roof" are due to special requirements by the city to decrease visual impact of towers." So apparently you called them tripod antennas too.
And the article you linked us to, refers to some cell sites, using NextG technology but not all. You are correct, cellular, also known as main cell sites uses panel antennas.
Panels antennas can be hidden but it depenRAB on a lot of factors which I will not bored you with.
Cricket has done a great JOB with their facilities and I would say that they have a great management. When you say other carriers and big tower (Monopoles) you would be surprise with how many there are. Granted no at much as the east coast but there are still lots.
Anyways, I am not here to hate on Cricket, because I do believe they have a place here in San Diego. I also believe in their business practice I am skeptical about the reception and NEXTG. I hope they last, and I hope they continue to expand here in SD.