Huge? 20' radius is huge?
Yes, in a moderate or smaller sized room, Silence can work. Mostly against PCs (since most NPCs do not cast spells).
But outdoors or in a large cavern, creatures can just walk out of it.
It happened in our game. The PC Bard cast Silence on the NPC Cleric the one chance she had to face off against a spell caster, and the cleric picked a ransom direction (DM rolled it so that she didn't seem biased) and the cleric merely had to use movement to negate the spell. It was about a 70' x 60' cavern.
Yes, it can be good against a very limited subset of NPCs in smaller areas, but mostly it's an anti-PC spell where the DM decides to nerf them in a small area. The DM decides the environment. Many of the PC classes are casters. And the DM sets it up.
So, the DM can MAKE it a good spell, but the players rarely get that chance (both because most NPCs are not casters and because most combat locations are decided by the DM, not the players). Yes, if the PCs face off against NPC casters in a small area or if the PCs can somehow limit the NPC's movement, it might work.
But sorry, you are not being objective here. You as DM set it up to be great (both with chosen environment and by spamming it). It's not great on it's own.
Please. Don't be insulting. It's beneath you. I have played the game, I have read other people's experiences here on the boards (and on other message boards). It's not just arm chair quarterbacking.
Just because you as DM easily screwed over your players with Silence by setting up a scenario does not make it a great spell. At least not for the PCs.
I'm running an officially published module which happens to be set inside a dungeon. Like a lot of spells, it's a fantastic spell used in the right circumstances.
I generally find a lot of people that find spells to be "useless" just either A) don't have enough game experience or B) aren't very tactical players in the first place.
Now your originally post was this:
I recently put together a Paladin for 5E and noticed that many of the spells requires Concentration.
Plus:
From my perspective based on how many concentration spells are in the game, one of several "fixes" should be done. Damage should not negate them, or casters should be able to have more than one, or many of the spells (like Web and the especially weak Silence) that are concentration should not be concentration. It's like WotC went into a feeding frenzy on spells. Between concentration and save every round, many spells barely work at all.
Doesn't sound you're very experienced to me.
Personally, I've been running a spell caster heavy game that has reached 14th level, and been playing in another game, and have also ran a ton of encounters against most of the monsters in the book all the way up to level 20. I think concentration is fairly well balanced.
You can take that or leave it, but I still think you personally need more experience with the game before you start tinkering with it. But hey, it's your table, knock yourself out.