Not only drop it, but they made it worse in versions after '98 and did really stupid things to it, like dropping recurring ToDos and Events! I completely rely on those recurring things, and it really pissed me off when I'd upgraded to a newer release and found they were gone - I immediately demanded a refund and downgraded.
That was years ago, and I have yet to find a manager that works as well for me as old Sidekick '98.