Totally agree.
I also think it's counter-productive personally. Whilst theoretically more games can lead to more injuries and more tiredness etc, winning teams also help to build momentum and fan interest. Our recent cup games have been dire, played before 4-5000 and losing. Does no good at all.
I would make a few changes, but otherwise send a strong team out against Pompey and try and make a go of a decent cup run.