Anyone who can truly use multigig (or even 1 gig) will confidently be able to say 'I need it because...'. It's one of those things where if you have to ask, you don't need it. As Armageus and Caged said, if you have a lot of heavy users and are pushing a ton of data off-site (large VM files, backups, video files / CCTV, software, archives, whatever) then you'll appreciate the upload that comes with such a package. If you have a homelab and are pulling and pushing a lot of data (multiple TB a month) then it will be useful in bursts. For a home user, most remote office workers and certainly for gamers, a 100Mb package will likely work just as well but save a chunk of money.
Your latency (ping) is determined primarily by the underlying technology type and your router. A 100Mb package and a 2Gb package on FTTP will have pretty much the same base latency/ping. If latency is your primary concern and you can't articulate why you 'need' 1-2Gbps, then you'd be better skipping the speed upgrade and putting that money towards getting everything on Ethernet or fibre on your LAN, and installing a proper router with real QoS (CAKE, fq_codel) and tuning that so that you avoid bufferbloat. I run VyOS on a mini PC (EQ12) with CAKE and push (and pull) 5-10TB/month easily, with 1.5ms latency to my servers 50 miles away in Manchester (effectively making my backups/pulls 'LAN') and a dropped packet rate of only 0.000009% for SQM after 10TB of transfers. I can be down or uploading a massive data set at ~1.8Gb/sec and the other five people in the house will be on a LAN party with 2ms ping and no issues. My DNS servers also report no latency spikes. My point is, I could have achieved those same latency sats on the 100Mb package too - the bandwidth/speed is a separate consideration to the latency.