Let's go through your list one by one
1.) Whirlfloc/Irish Moss
Not needed (and not allowed by reinheitsghebot, not that I'm a stickler for that) but it will help seperate the hot break out of kettle and may help improve clarity and head retention of final product especially if your pH is off.
2) Hydrometer readings (OG and FG!)
So, if you aren't taking the reading but you have hit your numbers anyway then, yeah, this isn't needed. It's just something for YOU to keep up with consistency. But let's say you accidentally omitted a pound or two of maltt? Wouldn't you at least like to know? Or if there is a problem with your efficiency and your gravity is extremely low you will not have any idea about it or what you could do to fix it. Also, when you bottle underattenuated beer you will realize how critical taking FG readings really is.
3) Fermentation Temp Measurements
Fermentation temp is critical to a beer. If you have an idea that a beer is at 64 or 66 because it is in a 60 degree room that should be fine. As long as you know the ambient temp you can have a reasonable idea what the fermentation temp is. But fermentation is exothermic and will be warmer than the ambient room so you will need a very cool room indeed. If your living room is at 72 degrees and you are doing nothing to control temp you are not making the best beer possible.
5.) Pitching Temperature measurement
If you pitch at 80 degrees and don't have a way to get the temp down quickly you are going to have problems. As I have tried to make clear: temperature is extremely critical and if you are giving it a "ho-hum" attitude then I highly suspect you aren't making the best beer possible. Some yeast strains are more forgiving than others, especially if you start them out cool. But temperature is definitely something that you need to be paying close attention to detail on.
When you taste the difference between a beer whose pH was off compared to one that is in the correct range side by side you will understand. Generally, for many folks, the pH will check out in the correct range or with very small calcium or acid adjustments.
7) water adjustments
No argument here: As long as your water is chlorine/chloramine free and it tastes good you can make very good beer. But if you are trying to make a pilsner with very hard water or a stout with very soft water you are going to have problems (especially if you don't know your pH!) If you have water with low to medium hardness like mine you can make any style you want though you will most likely find your darker beers will taste better with some calcium carbonate additions and you kolsch will taste better with some lactic acid and calcium chloride additions and pH check on both to make sure your additions got you in the range. Though I would argue that for pale beers such as pils and kolsch the beer is better when the water is built from scratch.
Now let's say your water is super hard and you are making a pilsner and you don't add any whirlflock to help aid in break clarification (and your pH was off so you have really murky wort that will cast a long term haze) and you use a lager yeast but pitch at 77 degrees and put in a 72 degrees room with no other temp control and you didn't take an OG reading but added 2 extra pounds of malt by accident then didn't take a FG reading and bottled your beer at 1.030 (unbeknownst to you) then, hell yeah you are going to have some problems. But even if that is the worst case scenario and you just fly by night and don't pay any attention to detail, but you at least "accidentally" hit all your numbers and your pH just happens to fall close enough in the range, you could be making very good beer, but that isn't the same as making the very best beer you can make and, at the very least, you will start to have problems with consistency especially if you are trying to brew the same batch over and over again.