Should Tesla have released the Model 3 before the Model X?
No, because they didn't yet have the battery capacity to support the volumes at which the Model 3 would sell. Heck, I'm not convinced they have the capacity now, two years later.
As I understand it, the Model X was basically filling a gap. The Roadster was introduced in 2008, the Model S in 2012, and the Model 3 in 2017 - there was a five-year gap between the S and 3 and Tesla wanted something to keep them in the news, more or less; hence the Model X in 2015. It sells at about the same rate as the S and has one fancy new feature (the falcon doors), but it's basically a Model S in "crossover" form.
The Model 3 is a much different kind of car and will sell ten times better than the S or the X - but it requires almost as many batteries per car, which meant that the Gigafactory had to be online first.
Tesla needed to make money from the S and the X before being able to afford to build the 3.
Also, Tesla has learned some good lessons about producing the overly complex Model X, going through "production hell" during 2016 with the Falcon Wing Doors and too many options for streamlined production.
Now they've greatly simplified the X and S options, and striven to simplify the 3 even further, so they can produce it in great numbers without hitting roadblocks due to complex features that would also reduce reliability.
Basically Tesla needed the money and the lessons from producing the X to make the 3 successful.
No, they could not.
A. They did not have the capital funding or branding to build and sell such a high volume car right away.
B. They needed the cost of batteries ($ per KW) to come down. I believe this metric is $100 today. When they conceived the S, it was about $500.
C. Of course, they could have done things differently from the get go that could have changed things, i.e the Nissan leaf was conceived as a mass market automobile from inception and even launched before the S - but Tesla has always been a premium car company. They prefer going for the big money first. So, also a preference from the company itself.
Humanity has a bizarre love relationship with what it calls a "Sport Utility Vehicle" (despite the fact that it is neither sporty nor utilitarian). Most car companies have been milking this stupidity by making ridiculous "SUVs" and selling them to all the sheep who think it makes them look cool.
Why shouldn't Tesla join the feeding frenzy?