There are two weapons commonly known in the Star Wars universe. One, the most famous by an order of magnitude, is the lightsabre. The second is the weapon of the 99%, the humble blaster. The blaster is a pretty nifty bit of equipment, which makes the sci-fi environment of Star Wars all the more immersive.
Blasters, especially in the original trilogy, are shown to be extremely powerful, punching through any armour with ease. They are also scaled up to the larger turbo and quad lasers (which aren’t lasers) and provide the backbone of all weapons. In the prequels, and then as far back as KOTOR and forward as the Legacy era, blasters are the majority weapon of choice. In fact, the amount of non-blaster ranged weapons is tiny and mainly reserved for those outside of the Galactic standard.
So blasters are the weapon of choice for almost everyone.

Why?

Ever since Return of the Jedi, the ability of lightsabres to block blaster bolts has become firmly entrenched in canon, and meant that Sith and Jedi are almost invulnerable to blasters except in large numbers or from surprise. It’s not like this is a surprise problem, lightsabres and blasters have been around in almost their current form for 5000 years of Star Wars canon. Admittedly in the time of the Galactic Empire this was not much of a problem because there were so few lightsabres. But aside from that 30 year bracket from ROTS to Luke’s Academy, blasters have been mostly ineffective against skilled Force users.
This is even without mentioning that in a battle with a Jedi or Sith, most casualties are caused by reflected shots, not lightsabres directly.

Blaster weapons are, in comparison to Earth bound weapons, slow to fire, inaccurate and reveal the shooter easily. This is a point not just made by the movies, but by games and other EU material as well. Blaster rifles also have much reduced accuracy, 100 metres effective for the E11 with a max of 300 metres. By comparison, the M16, a rifle made half a century ago, is accurate to 500 metres, with a maximum range of near a kilometre.

There are reasons of course. The incredible hitting power of the blaster makes most personal armour redundant, apparently much more than any conventional weapon could. The blaster is repeatedly stated to be a rugged design, easy to repair, and reliable. The weapon also fires a hundred shots to the power pack, and five hundred to the gas cylinder.

Do these balance out? Is the loss of accuracy, ability to be reflected and low range off set by mass production, ease of use and rate of fire?

If anything this reminds me most of the transition from bows and crossbows to gunpowder weapons in the 15-16[sup]th[/sup] centuries. On the one hand the crossbow and longbow were delicate, accurate weapons which required a great deal of training, and which lacked penetration. On the other hand was the early arquebus with its shorter range, high visibility, but also ease of use and penetration.

The big difference is that this transition on Earth was largely over by 1600, whilst the status quo has remained in the galaxy for almost 5000 years. On the one hand the answer is mostly narrative. A rapid firing, accurate blaster would certainly have meant the end of our intrepid heroes before even the first Death Star fell. On the other though, perhaps it was desirable for first the Republic, then the Empire, to have a mass produced lethal weapon which its lightsabre wielding leaders could usually defend against. Perhaps there was not a little coercion to maintain the status quo.

That’s why the boltgun rocks….