The -200/ER is one of the most ubiquitous 777 variants. Many, many airlines still fly the -200/ER (think UAL, KLM, BAW, SIA, AAL, DAL, AFR, ANA, JAL, CPA, KAL, etc.) The -200/ER has 516 total airframes both flying and ordered (according to wikipedia), whereas the -200LR itself has "only" 57 frames flying and ordered. The -300/ER has 661 frames total, so I understand the demand for that airframe.
I personally dislike the blended winglets on the -200LR/F and -300ER, and would be ecstatic to be able to fly the -200ER for my virtual airline.