We should not confuse celebrating Easter with celebrating Christ's death and resurrection. There are a number of Christian religions who do not observe Easter with its pagan traditions....but do celebrate the death and resurrection of Christ.
Carla brings up an important point, though. The majority of JWs do not partake of the emblems and, thereby are denied sharing in the symbolic "body and blood" of Christ. This is by far the more serious infraction of Christian worship.