Quite a few angles on this issue alone.
One, a party bothers to have a tough candidate selection because it wants to give Singaporeans their best. This should be applauded. Any party that does not do this is not serious. We can question the result - for example the PAP's tough candidate selection churns out moneymongers because of the values of the party. But having a selection process is good. A party can only field 87 candidates. There are probably 100,000 people in Singapore with "polished background" of which 500 are interested in politics. The next criteria would be their character, especially if you can be a team player. Moreover, you should not select 87 of "polished background" or you would become elitist. Which means at most 50 seats for these types and 37 from the rank and file (ITE grads, common engineers etc.)
Two, a strict candidate selection is not an impassable candidate selection. Very few who are really good will be turned down by the candidate scarce opposition. CSM, Daniel Goh and Leon Perera have made the mark. Leon joined when it already has 7 MPs and a bundle of potential candidates but he did not seem to have a problem being identified. No one knows what TJS issue with WP is but there are people saying he is self centred; I am hazarding a guess that could be the answer.
Three, candidacy is not the only way someone with "polished background" can contribute. WP has a retired colonel, a female lawyer from a top firm and several other university graduates of different trades who have never run for an election. Lee Lilian did not join WP for candidacy, intending to do grassroots work all her life but was identified as candidate and we know she became a MP and failed N Levels.
The new party has less than 2 years to prove itself and I wish them the best. People said the same of RP in 2008 and we knew what happened in the end. Filling the gaps is not the only way a party should exist for. Although TJS is not KJ, they are not easy to work with. Nicole Seah can attest. KJ by being the top of the list merely hastened the process of a self-destruction.