Anything coming off a Detroit production line is going to be a compromise between what we the consumer want, desire and are willing to pay for; what the government mandates concerning EPA regulations, fuel economy and safety; and how much is the potential profit margin for the builder against potential liabilities. Nothing will please everyone all the time but overall they do pretty good.
There are plenty of aftermarket bolt on stuff for the past and current big blocks that can improve performance but you have to understand you can't get something for nothing. There's only so much energy in a given volume of fuel be it gasoline, diesel or rocket. Those added horses need to eat. Banks has a very nice set up with everything you'll need in one box. It's pricey but Banks has a good rep.
The spark plug problem with the V10s is unfortunate for us the end user. It probably looked good on the drawing board but its pretty difficult to predetermine all the potential pit falls of a given design. Even harder to change the design once production has started. Ford did come up with a fix that doesn't costs them (or us) very much and is pretty simple to accomplish. May not be the very best but lucky for us we can take our engines anywhere we want to get them serviced. For my generation V10 I don't have to worry about the threads stripping but instead that the spark plugs may crack in half when removed. At least the plugs are rated for 100,000 miles. Only 65,000 more to go before I have to slay that dragon if I don't crack a header first.