I have 175 Mbps symmetric at home, and it's good enough for my purposes at the moment. Having reasonable upload bandwidth like that with 3 ms ping to the office is useful for exporting X apps to my work desktop (yes, I do that). It's nearly as fast as a local app to the point where I could forget it's remote.
The decent upload is also really handy for doing remote backups. I have ISCSI targets in distant locations that I simply mount and use like a local file system. ISCSI without reasonable upload capacity or low latency is a frustrating experience.
I used to have 50 Mbps symmetric, and it was okay, but I did find myself waiting on things. I wait less now with 175 Mbps, but I'm also still throttling backup speed.
Most websites I visit don't fully utilize the bandwidth because of the TCP ramp up time, and generally downloads will finish before maximum speed is reached. Well designed services like Mega will easily saturate my connection though.
With a 1 Gbps connection at the office I've seen download speeds up to 80 MB/s from a local free software mirror. It's handy to download a new distro ISO in 15 seconds. It really changes your perspective on what data is worth keeping locally.
If I were regularly downloading and uploading multi-gigabyte files, such as backing up video, 10 Gbps would be very useful! If online storage prices keep dropping it will be very tempting to keep everything in the cloud. Right now the cheapest storage VPS providers are around $20 per TB per month.
But the key point is not so much increasing download bandwidth beyond 1 Gbps, but increasing upload bandwidth to match.