Joking that he would've still made the offer sheets if his mother was GM of the Oilers, it's clear that the Blues really believe that Broberg and Holloway are part of their long term plan for success. Shortly after the decision was made official, Broberg's agent Darren Ferris revealed that multiple more teams were interested in signing him to an offer sheet.
These two offer sheets were aggressive against the Oilers in a vulnerable salary position, and make sense as financial commitments to two promising young players. Both Broberg and Holloway haven't yet played a full NHL season, but they really broke out in this year's playoff run and seem to be primed to take the next step to become regular players - potentially even impact players.
It's tough for the Oilers to see these two players depart the organization when they're just beginning to reap the benefits of their development. However, it's not like either Broberg or Holloway were the essential components to winning, and the team has to set their priorities. By not matching the offer sheets, the Oilers gain some salary cap space and draft picks for a future trade, and they'll still be favoured to go to the Cup Final.