There are many situations, so it's hard to synthetize it quickly.
Many points have been adressed.
First thing, we are talking about Professionals so, far from my concerns, they don't mind about cost, weight, number of devices....
I think we should separate old guitarists (as Knopfler ). They have achieved their rigs during years when there were no such profilers/modelers....
They don't talk about it cause, i think the need doesn't come directly from them. I assume that the sound guys advice him/them to play with it to be more reliable/repeatable whatever the rooms.... The settings are quicker.... Guitarists just have to be reassured their sounds and their feelings will be the same as before....
For the younger, why not just a Kemper ?
I think some can only play on one amp with few FXs so they don't understand the need of having a sophisticated pedal, they know exactly what they want, i understand and respect that....
For the rest, i imagine it's lazyness, they've been influenced or snobbery...
It's more glamour (a kind of heroic quest to say) ; "i've choosen this particular muff, disto, etc.....cause i've tested hundreds of pedals and i love the result with this specific one....for the delay, the same and so on.....They've spent a lot of time to work out their pedalboard, Wahou ! Bravo !
I feel like there's a kind of denigration about digital stuffs, it seems like the work is so easy to do....
I meet the same with digital camera ; cause everyone has good cameras even on their smartphones, they think pictures will automatically be beautifull....NO, the tool has evolved but you have to acquire knowledges.... The position, the settings you choose will have an impact on the result...
Even a Kemper needs time to obtain the sound you want....But it's boring to say, i've gone on rig exchange, choosen JCM800 from XXX, set the parameters this way...Put a Kemper drive, etc...
It'll be easier to summarize all that.... You won't talk about Kemper's shop to receive your Stage
On the other side, i think we are paradoxical too.
Modelers/profilers offers the possibility to be so versatile with a huge amount of amp/cab sims and some of us plug and play devices through tube amps or cabs with one particular speaker (V30, greenback, etc)...
The question of ease and weight is another thing, a guitar, a modeler and plug it directly in the mix table.... And no ; i bring my Kemper Kabinet too....