I hate fanservice chapters like this.
Why though?
A good question to ask yourself when determining if fanservice is acceptable or not is "would the material lose anything if the fanservice shots were removed?"
In this instance, I would say nothing would be lost. We could have the same chapter, with the same dress up scenes, with the same cuteness, but not have any underwear shots. The focus of the chapter is a bunch of girls having fun trying on outfits. To me, the primary part of such a scenario like this would be the outfits and the girls' reactions to them.
What relevance did the bra and panty shots serve towards the chapter's theme of "girls having fun trying on different outfits?"
None of the dialogue referenced their underwear. It would have been borderline acceptable if they were also picking out underwear that went with the outfits they were trying out, but that wasn't the case. The underwear shots existed specifically as fanservice without any relevance to the chapter at all. Fanservice for fanservice sake. I hate that.