This is the hard truth about the WP:
When JBJ was in charge, WP could only hold Hougang. Most people admired JBJ for doing the dirty job of whacking PAP. Nothing more. People, after whacking PAP, still want PAP in charge.
In recent years, the reason why WP has been gaining votes is because WP has been behaving like PAP. People feel assured with WP because they see a PAP-style party, but wearing blue. WP under Low Thia Khiang was smart enough to switch strategy to win the middle ground.
If WP behaved like a mad dog party like SDP or RP, WP would never had been able to win Aljunied GRC or Punggol-East, and garner over 40% of the votes wherever it contested.
As such, do not expect WP to oppose PAP too much when it comes to national policies. SDP has come out with countless national policy papers and even drafted shadow budgets. But people still don't give them much credit simply because they do not behave like PAP. They don't have tight discipline and they have too many loose cannons or unreliable candidates who jump from party to party.