Riding pleasure is important, and from that point of view a better bike will be an improvement for sure.
It's perfectly feasible, but it will come with trade-offs. It depends at the end on your priorities. One of my ex-colleagues was commuting on such a bike, he is a convinced roadie who participates to races. But his commute was in the 20 miles on secondary roads. Because of rush hour, the duration was similar than going by car or by transit. He wasn't also commuting daily, so when he was coming by car, he took sets of spare clothes to avoid having to carry them when coming by bike.
Personally, I would consider this bike not overkill but inadequate, for several reasons:
- commuters should be more dependable bikes, you ride in less optimal conditions, and with more traffic: sometimes, you won't be able to avoid the pothole because of the more dense traffic, you'll be happier to have 40mm tires rather 25mm.
- the benefit of "better bikes" are mostly appreciable after longer distances. Sure you will notice the differences in term of compliance and weight. But on a 7 miles commute, the differences shouldn't have reached a point where they become tiring.
- sport bikes are sport bikes: you don't have racks so you'll need to carry your stuff in a backpack (which I dislike a lot), saddles are usually designed to be used with a padded short, a $2k bike usually has clipless pedals, so you either need to carry civilian shoes with you or make sure you have shoes at destination, no chainguard to keep your trousers clean... So the benefit of the "better bike" may be offset by practicalities.
- I would also happily trade-off a bit of weight for ease of maintenance on a commuter
- some accessories are appreciated in a commuting context, that I don't want to fit on my fun bike: fenders, racks, chainguard, reinforced tires, kickstand, lock...
My ideal commuter would have the following characteristics: 40mm tires, hydraulic disc brakes, belt drive, internal hub, hub dynamo, fender, rack, comfy saddle and some form of compliance (either suspension or carbon fork/seatpost). Quite far from the TCR ...and can be in the same price range.
Note that the notion of fun is also very subjective: I enjoy riding a comfy trekking bike - 40mm tires, front suspension and suspended seatpost (but a more slanted position than what you usually see for this kind of bike — but not too slanted to have a good visibility): it's the "I'm flying over the road" fun (I took this example because I have such a bike, not because I consider it's the best option). But for other people, the kind of bike I describe is boring and only reactive bikes are fun, and those are willing to tradeoff practicality for that. A sport carbon bike would be a better choice then.
That being said, the real upgrade in term of experience for commuting for me is an e-bike (a light an nimble one), not a race bike.
If you have space for 2 bikes, the best option for me is to have a dedicated commuter and a nice week-end bike. If you can only have one and it's mainly your commuter, up to you to define your priorities, but just be aware of the compromise.