What managed VPS does is give you a pre-tuned hosting environment that fits most sites out there (with varying levels of aggressive caching enabled). If you’re coming from shared hosting, any VPS will be a noticeable performance gain to you. But where managed VPS can be a turn-off is the price. You might pay upwards of $30-500/month for a server that you could have leased yourself for a quarter of that.
Think of it this way, $80/managed gets you either: 6-core server unmanaged VPS and you have to set everything up yourself, or 2-core VPS with everything pre-configured. Most techies will choose the 1st option and set-up the server themselves or hire a cheap sys admin somewhere around the world to provision it for them.
The route of going unmanaged is indeed much cheaper and potentially offers superior service/functionality in the long run since you have full control (but also full responsibility) of everything. Being that you don’t plan to learn any bit of server management, it’s not a bad idea to always have a programmer and sys admin you can hire from time to time to manage this for you. You’ll only need them a couple times a year and you save more money paying them only when needed rather than to pay a managed VPS company a ton of money upfront.
However, some folks really do prefer the convenience. It’s like choosing to build your ow PC vs buying a Dell/Apple and it comes with warranty.