Agree. I rarely get Cloaks. If you play a couple games with Sentinels and/or Legolas in an Elf Cloak you will get a good idea of how often they matter. Some...but not a lot.
The only time they really paid off for me in numbers was during a set of events at our local store where we played a series of individual games over a few weeks and totaled up points for final victor. Each game had a different scenario and you could tailor your army but they were all 500 point lists. We were playing Contest of Champions where each side's leader is trying to score more kills than the other. So the duel objectives of making kills while robbing your opponent of his. I was facing Isengard with Lurtz leading a big group of Uruks (including some crossbows). My army for the tournament was Wood Elves and you can find yourself packing a LOT of good targets for Lurtz into a 500 point list normally. So instead I took Legolas and Radagast, a couple Sentinels and all my WEs got Elf Cloaks. Major point sink so I had very few models on the table, but also completely crippled Isengards plans to shoot (he instead just charged everyone forward).
Legolas easily scored several kills with his bow fire and as Isengard got close I used the Sentinels to keep other Uruks in the way of Lurtz while Legolas continued to rack up kills and I slowly fed my Wood Elves one at a time against multiple Uruks to ensure they were killed off before Lurtz could get to them. In the end Lurtz had zero kills, Legolas several (including Lurtz) and I had a Major Victory. A little Cheesy yes, but there was a bit of bragging going on in advance, my opponent was a great player and the friend that got me into the game, and the surprise on his face when he realized what was unfolding was priceless.
This was just a specific example, but in most SBG games, I may only give a couple WEs the Cloaks if I need a "covert strike team". I'd say 9/10 times the extra models are far more effective.