Speed and simplicity. Case, accent, kana, and other insensitivities cost you in CPU cycles that could be spent doing something else. I don't think it's nearly as big a deal as it was 3 decades ago when computers were running at 4 MHz, but it can still be a serious undertaking to get right -- especially with international character sets.

For instance, in a case-insensitive system is capital E the same as a lowercase é with the accent mark? You also have to create sort orderings, etc., for case insensitive systems. This is why SQL Server has so many different collation settings and why XML is case sensitive -- all of these things are factored in.

For a company that already has the code base in place for all this (like Microsoft), it shouldn't be that big a deal to incorporate these options into other products like SSIS.