I would assume that such planets have a very large surface area, larger than Earth and Mars combined? In this case, super-Earthlings have plenty of exploring to do, just in a different way from us. It can still be challenging and time consuming, for example air travel may not be practical, or may require balloons floating in denser atmosphere rather than jet engines. By the time we explored Mars and they explored their entire surface, or prospects for going further may not be so different. Either we have developed technology to travel much further, or we have to accept that that's all the planetary surface we are going to see and we better take good care of it.