I would absolutely agree with this. If I had everything to do over I would have unlocked the Geonosian Soldier, Dooku, and Old Daka at the beginning and leveled them up. I had such a wayward sparse team until the Yoda events.
You will clearly need teams for both the light and dark sides, but you have to keep an overall strategy in mind. A strong leader with good leader abilities, at least one tank, two attackers, and a healer of some sort. These will get you through the single player campaign modes and open up your ability to farm characters and gear. They will also be crucial as you develop teams for the challenges.
The other thing I learned later on, don't squander your ability mats over multiple characters. Focus on one, then move on to the next when they are complete. It just slows your progress.