Gnumeric is a large steaming pile of dog poo. Do a sort on a largeish file and it will consume all the known RAM in the universe. Do the same operation in Excel and it barely breaks a sweat.
I might misremember the number of columns (could have been 20,000 - also, it had many rows), or maybe the 16,384 column limit applies to xls(x) files only, not to importing CSV files.
I remember at first cursing at Excel, then realizing what a ridiculously large number of columns the file had.
Provide a proper test case to the developers and they will likely fix it. I've had extraordinarily nice experiences with bug reports to gnumeric so far.
I'll admit that I only deal with that many columns on very rare occasions, but it does come in handy sometimes.