There's a good reason that gigabit ethernet is 1000MBit/s and that's because it was defined in decimal from the start. We had 1MBit/s, then 10MBit/s, then 100MBit/s then 1000MBit/s and now 10Gbit/s.

Interestingly, from 10GBit/s, we now also have binary divisions, so 5GBit/s and 2.5GBit/s.

Even at slower speeds, these were traditionally always decimal based - we call it 50bps, 100bps, 150bps, 300bps, 1200bps, 2400bps, 9600bps, 19200bps and then we had the odd one out - 56k (actually 57600bps) where the k means 1024 (approximately), and the first and last common speed to use base 2 kilo. Once you get into MBps it's back to decimal.