You have to hold onto a TOTL keyboard a lot longer than a MOTL one to fully make it worth while. One of the reasons why I stuck with my G1000 for well over 10 years, have happily used my G70 for eight (and counting, at least for live use now) and anticipate my BK-9 quite possibly going to the end of my career (and that isn't even TOTL!).

That and familiarity and intimate knowledge of how to wring the best out of it without the manual..!

But I agree, MOTL arrangers are becoming so incredibly good, capable and affordable, they often make the TOTL choice a bit pointless. Often, the few things the TOTL adds are things like samplers so few of us use, paying an extra $2000 or so makes little sense...