Yeah, but there's always a bigger fish. TH9 with legos still get 3* all day in war, because a TH10 army with a jump or two, or just the correct number of WB are still going to tear your base up.
Legos definitely offer you more protection in normal multiplayer, because people can't gameplan for you specifically... but I mean, when you have the resources, the big fish is still going to come get ya. I find that infernos are a much stronger deterrent than legos, when farm/raiding.
I consider it entirely reasonable to ♥♥♥♥ up to legos OR to up town hall early, when every defense is maxed, etc... just depends on how you like to spend resources, and how you like to farm. It's a total coin flip. I went TH10 when I was only half skulls. Then I evened out all of the new stuff to the level of the rest of my base, and started walls again... skulls will be done in a week. I haven't seen a downside, because at TH9, most of the attacks were hogs or loonions, (walls were immaterial) and at TH10, most of the attacks are loonions and a few GoWiWi--and multi mode ITs properly placed handles them.
IMO Planning for the future should just be a matter of "don't upgrade until defenses are maxed," and really, there isn't a big downside to being a slightly premie TH9... the trouble doesn't really happen until you hit TH10.

