Edit: Unnecessary not necessary. I'm questioning their necessity.
This bike shop repair guy was trying to get me to spend more money in his shop by convincing me that my bike was too plain and needed some extra oomph. He was telling me about how important it is to add to and beef up a long distance commuter bike so that you are prepared for anything. Maybe he didn't know that I have been riding for some time now in all conditions and have dealt with almost every condition of the road there is to deal with and fared well under each circumstance. I let him talk but explained to him at the end that I had no desire to beef my bike up nor add anything to it. I ride a bike with minimal additions. The less weight the better. I want my bike to be stripped down to the core as close as possible. As weightless as can be and as simple and easy to maneuver, manage, and transport as possible.
If I could get away with no lights, i would too however some compromises are needed. I keep lights, a bike chain, and a tube pump as the bare minimum. I need not a water bottle because I make sure I eat and drink a very decent meal before any and every ride if possible. That way by the time I am on the road, I never get exhausted nor dehydrated and have plenty of liquids to burn until the next rest stop. I carry a very durable book bag that does get sweaty very often. But it is a necessary hindrance and I make sure to always keep lotion, cloths, a change of clothes, and hygiene products in the bag at all time in case I need to clean or change up if necessary.
I feel a book bag is a much better fit for a bike than a pannier or rack. I feel the added weight to the bike would make the bike more difficult to maneuver. The weight on the shoulders is still heavy but without the added weight of the rack and the pannier, I feel it is more simple for just a shoulder bag. 2 strapped book bags over messenger bag as well makes for a more sustainable ride.
As far as the fenders and whatnot, I feel this is also an unnecessary addition. The worst part about riding in the rain is the water splashing back up as you ride. However if you have a water proof bag and a water resistant rain coat or something to deflect the rain splashing back up, by the end of your ride, you should either have a fresh change of clothes or in all, dry clothes underneath everything.
The point I am making is this. A simple backpack and extra layer of weather-proof clothing is usually all that is needed. All the other additions to commuting with a bike seems nice and probably makes bike companies a good deal of money promoting to some riders as if it is bike necessity, but it may not be a necessity for everyone. A feel good planning and a little creative ingenuity goes far longer than advanced additions.
Also since we are on the subject of additions, what do you think about fixed gear bikes? They to me are the most simple a bike can get. The only reason I ride a commuter bike over a fixie is the fact that they seem dangerous and unfit for long distance rides in various terrains. But I have been considering switching from the geared to the "gearless".