The 30% cut was considered very good at the time. It was way better than the 50-90% cut that traditional publishers would take.
A sibling comment notes that Steam charged 30% at the time (though some had better deals) but it's worth noting that Steam was not an open platform that anyone could publish on. Much like for consoles, to put a game on Steam you had to have a preexisting relationship with Valve, or try to develop one with no certainty of success. This was also considered a very generous cut because getting on Steam was almost a guarantee of financial success.
A sibling comment notes that Steam charged 30% at the time (though some had better deals) but it's worth noting that Steam was not an open platform that anyone could publish on. Much like for consoles, to put a game on Steam you had to have a preexisting relationship with Valve, or try to develop one with no certainty of success. This was also considered a very generous cut because getting on Steam was almost a guarantee of financial success.