Lightheavyweight was a shark tank when Jon Jones was on the rise and his starting several title diffences. It didn't start getting shallow until people started moving up and down in weight for a chance at becoming champion and leaving for bellator, which all happened in 2013.
Even after the division became "shallow" there were still a few big names who would have crushed anyone in the couture tito era I.e. Gus Rumble Cormier to keep the division interesting
Also Teixeira was hot before Jon Jones ended Teixeiras 20 fight win streak!