1. Joycons are fine for what it is. The lesser quality plastic, the better. Why? Joycons are more prone to damage, and is easier to replace. Frequent replacement of parts meant the Joycons need to target at less than $60 for a pair, in order to say it's just right. If you want premium Joycons, and you often damage them due to putting it on uneven surfaces, or you dropped the Switch from a fair amount of height, you're going to have a bad time...
2. Battery technology hasn't improved over the past, what, 5 or 6 years? There are no big breakthroughs that would scientifically make small capacity batteries lasting 1 or 2 hours more than the current designs. So, if you want longer battery life, either you opt to increase the size of the battery (thereby increasing the overall size of the Switch, and reducing its portability), or you go with external power sources. Choose wisely.
3. Batteries can be replaced, however, this also meant the components inside the Switch must be internal combustion resistant, therefore requires more vigorous testing, design, implementation, and a price hike to compensate the return of investment in researching these safety mechanisms and hazard prevention. But if you still insist, without changing anything else except for the option to replace the battery, expect a $50 increase.
4. Integrated NAND memory chip is pretty expensive. It is not like disc drive platters, which are far more cheaper by capacity/price ratio. A Fujitsu 128GB hard drive is $24 to $30, compared to a 128GB USB drive, which is in the range of $70 to $100. But sure, at least having an option buy a cheaper (current) Switch model or a Switch with a larger internal memory, is a good compromise. Besides, we have seen teardown videos of the Switch's internal memory chipset being replaceable, so we should expect a model with a larger memory soon.
5. The dock is fine for what it is. Why would anyone wanted to see their reflections from the Switch's screen while they are playing on the TV, and the Switch's onboard screen is turned off all of the time?