WP has no reason to step into the GRCs/SMCs they lost because it might be gone (redrawn) next election, no base like RCs, PA, CCs events/organisations to actively be in the area, no mandate from voters to stay in the area, no town council duties to stay in the area, no funds to walk the area weekly, change in work life and personal life etc.
For smaller political parties like WP, fluctuation in candidates are normallly greater than PAP in each election especially for election losers as 5 years is a very long time. They have to get on with their daily lives.
Most times, election candidates end up as a one-chance kind of thing and if the voters did not give WP candidates the chance to serve in that election, most likely voters might never see them again due to age, work, family etc as they have no stable safety nets like GLCs, Civil Service, NTUC etc to give them a life.
This was WP's best slate of candidates in 60 years and voters blew it. Dont have high expectations to see the WP Punggol and Tampines Teams again in GE2030 plus expect more walkovers in future elections as more good people are discourage by election results to join WP.