Trip to Busan/Seoul

Hey people!

I’m currently planning a trip to Busan, then Seoul, around mid of next month (April 2025).

Based in Singapore, I just found out there’s a direct flight with Jeju Air to Busan. I did not know this previously and kept researching for SIN-ICN, then taking the train to reach Busan. This means I will book 2 one-ways and fly SIN-PUS, then ICN-SIN for return.

My question is, is this direct/simpler method better, or is there a reason why so many people take the flight to Incheon first, before heading to Busan from there?

Thanks in advance!

P.S. This will be my first Busan trip, so welcoming any suggestions too! :)

Edit: Thanks to everyone for your replies! I will take direct to PUS :)