A J-frame with large rubber grips can be a bit on the big end of things, granted.
One with either shorter rubber grips, or wooden grips, can be smaller.
Sometimes that may be just smaller 'enough' to make a difference when it comes to carry method.
I don't have an image of my J-frame still equipped with wooden grips, but here's some thumbnails of a 642 w/standard rubber boot grips and a G26.
The first couple of images do seem to show the J-frame having an approx equal 'length', as well as a 'longer' grip ...
This next pair of thumbnails show a different view, however, and one which shows why the J-frame can fit in more of my clothing pockets (w/pocket holster) than my G26 can, and have a reduced potential printing profile ...
The J-frame is slimmer overall and has a less blocky/bulky contour than the G26 in a couple of important aspects.
However, if the user can't consistently, accurately & effectively shoot the J-frame without using the older style bulky grips, then it may well become a moot point.
Overall size, preferred carry method, ammunition capacity, caliber/cartridge, controllability & reloading requirements are all arguably important considerations when selecting a lawfully concealed defensive weapon. However, the priority of the relevance of these factors may come together in different combinations for different people, and/or different combinations for even the same person in different circumstances.
This is one of those individual needs/risk assessment issues.
If I could conceal my G26/27 or even my CS9 in the same manner as one of my J-frames when concealment is made difficult by my normal manner of dress and activities, then I'd still be carrying one of the pistols all the time.
I'm long past the point where I feel inclined to 'dress around' my off-duty weapons as a matter of course. I have to do that everyday in my plainclothes assignment. If need be I can certainly dress to accommodate a larger weapon on my own time, if I perceive a potential need to do so ... but I generally prefer to relax my casual dress, and this commonly means a T-shirt in the summer time ... (and I don't find the stuffed-inside-the-groin/inguinal-area even remotely comfortable, especially when sitting & riding).
I've found the occasional situation when I've traveled with both a G26 & J-frame, so I can have alternatives.
I've also found myself choosing to carry a pair of J-frames in certain circumstances, and even that has been surprisingly easy to do and comfortable.
Different strokes.
I like options.