Except that it’s exceptionally expensive. 5e is probably the most forgiving with its currency, a Raise Dead spell costs only 500 GP (assuming no extra fees) and while it’s hard to approximate wealth in the game I found an old Reddit post that approximated it to ~1 GP = ~$1,000. So $500,000 minimum for a Raise Dead.
While there are probably people in your life that would sell everything to bring you back, would you really want them to? How many times could your family and friends pull together $500,000 to raise someone in the group?
If you’re so obscenely wealthy that you could afford multiple Raise Dead in your lifespan you’d have other, more political problems. For example you’d have people lined up down the street asking you to raise [insert tragic story].
Speaking of Political problems, you have to find someone willing to raise you and someone willing to finance it. If the king dies and the Prince takes over what are the odds that he’s going to raise his dad and give up that power? If he’s a bad king it might be hard to find a cleric willing to do so and even if he’s a good king a benevolent cleric might not have 500 GP to finance it himself. You could leave the money with a cleric you trust, but he could always just keep the money. If the Prince isn’t willing to Raise the king he’d also probably go out of his way to hide, protect, or destroy the body to make a Raise Dead by an outside source more difficult.
In setting I think you’re right, a good person, who is exceptionally wealthy, can probably ignore death. Someone like Lord Nasher from Neverwinter probably doesn’t have to worry about a simple stabbing, someone will Raise him in 10 min and probably be rewarded 100 fold. However, if you’re able and willing to attempt that sort of assassination you’d also know how limited the effect would be and probably wouldn’t even try something so simple.
I don’t know if 5e has starting age tables? 3e and Pathfinder do, it’s an optional character creation thing that helps show the general age of most things. It starts off with the starting age of a given race and then has a table with different classes and dice. So for a human the starting age is 15, Barbarian/Rogue/Sorcerer is 1d4, Bard/Fighter/Paladin/Ranger is 1d6, and Cleric/Wizard/Monk/Druid is 2d6.
So a typical cleric starting age would be 16-27. At that point they are a level 1 Cleric and have a grand total of one level 1 spell per day. 5e is more generous and gives them two level 1 spells per day.
That spell should do a lot, and in a small village would be amazingly effective, but at a certain point there just aren’t enough spells per day for everyone. It should actually be hard for adventurers to get healing because the local cleric should probably have spent all his healing for the day by the time they get to him, he can probably squeeze them in tomorrow when he’s recovered spells.