I was more interested as to why the OP hadn't taken his sports bikes down the B roads of Hertfordshire, Essex and the other higheays and byways of rural East Anglia; there being precious little fun on many of the A and M roads.
But to address your observation. On the contrary, Bill, I had outright sports bikes whilst I had the GS's and enjoyed them both together. The GS was (and still is) probably the easiest bike to ride, in that it is incredibly well set-up right from the get-go. It is only since letting the GSA go that I realise what a forgiving beast it really was. I would own another or another bike in the same GS family quite happily, not being too fussed about the cubic capacity, nor Power Commanders in an attempt to boost a GS's power. If I wanted power, acceleration and handling, I would buy a litre sports bike and save myself some time, effort and quite a lot of money. In short, the GS and in paricular the 1200 are bikes that flatter the rider, getting one out of trouble far quicker than they get you in. That is not a bad thing.
I sold the GSA to buy the GT, that is true. The reason was not the outright power, it was to do with the usage I could make of the bike as a whole. I do little riding in the UK, my bikes rarely turning a wheel. Nor do I enjoy 'bimbling' for bimbling's sake. But, clock up about 15000 a year on the Continent on assorted jaunts or recce's for jaunts. Most of that will take place on good mix of D roads, the equivalent of our B road system. What I got bored with on the GSA was all the bits and bobs hung off it, probably the 33 litre tank and the excessive luggage capacity, which only encouraged me to consider taking more tat with me. I never ran around with the panniers on but empty as that is just carrying air, which we are not short of in nature and was unhappy (if that's the right word) only really ever having them a fraction full when when going away. I don't buy duty free booze or fags, so couldn't even use that as an excuse, nor did I need to take two dress suits and full back tie. I wasn't going to go outright off-roading, so didn't need to pretend that I might. So, I went for the GT, which offers as much fun down the country roads as can be had with your trousers on, has everything (in essence just my GPS) built in, looks OK without its integral luggage (more often than not I just sling a smallish soft bag on the back) and has all its functions controlled by the iwheel thingy at the flick of a thumb. The GT has a tank size of about 24 litres, so more than enough for most normal usuage. Down the D roads it will return in the mid 40's MPG which gives it a quite adequate enough range. It does though drop to the low thirties if you sit at 120 down a motorway, but that doesn't happen that often. It's a bike that can make you incredibly lazy; you can blast overtakes
and trickle right down in 6th if you really want to. But it
will bite you if you don't concentrate some times, which makes it great fun, too. That need not be a dramatic bite from unleashing power, but just something as simple as forgetting that you trickled up to a junction in a higher gear (as the engine will let you) then wonder why it trys to dump you on it's side when you turn left at the the traffic lights in the wrong gear!
I also bought an F800R which really has no power at all, a small tank of just 16 litres and a chain. I use it for
just the same things as I used my GS's for and the now the GT. In many ways it is the closest thing to a 'real' or 'proper' motorcycle I possess and much closer to the bikes I grew up with in the mid-70's. It's simple and fun, only requiring a bit of thought and effort to get the best out of it. I also looked at the Honda 600 Hornet and the Triumph 600, which are much the same, maybe with a bit more power. I had owned a Hornet before, in parallel to my Blackbirds, so knew it was a good bike. The Triumph was nice, but every man and his dog has one. The BMW was the simplest, was suitably quirky (the chain running down the offside) and not quite so run'o'the mill as the Honda and Triumph, along with a generous service interval.... I also benefitted from quite a good incentive agreement between Lloyd's Motor Club and BMW Park Lane, which was nice. The only thing it suffered from when pushed harder down less than perfect roads was shonky suspension, which really had to go.
So, to the OP, enjoy your new bike and above all enjoy the local B roads you are now discovering. A penny-to-a-pound says you will enjoy them on a Mille too in the future..... As you will get used to them and the GS gradually builds on your confidence

It really is a very good bike.....