So, rushing in and of itself isn't bad and anyone can play the game however they want so I could care aless if you rush or not. If anything a "rushed" base is much easier to farm from, so please everyone rush. (just kidding)
For every TH level there are pro's and con's to going to the next level. In many cases the pro's far outweigh the con's, so rushing is actually better. Your playing time and style also come into play. For example, if you're playing 10 hours a day and only log off once for an overnight shield then your defenses are pretty much irrelevant, versus attacking once logging off, attacking an hour later, logging off, etc. With that syle, your defenses are much more important.
The main determent to rushing is how it effects your ability to obtain loot and your ability to keep the loot you already have. As others have mentioned, there is a loot penalty applied when you attack bases that are lower than you. If you're a TH9 and attack a TH9 or TH10 you get 100% of what's possible, if you attack a TH8 you get 90%, and if you attack a TH7 or below you only get 10%. So, if you rush to TH9, but only have TH7 level troops then you're in a world of hurt because you're forced to farm down, but everything you get is much less.
Then if you have a playing style where you're not on a whole lot, you take it in the shorts because TH10's and TH9's are 3 starring you every single time with a higher loot cap. Meaning they take more of your loot and they take all of it available.
The rule I use is what to I gain versus what do I lose on the farming side. I rushed to TH7 really early because the 4 camps made a huge difference in farming and I play quite a bit, so I wasn't too worried about my defenses. I stayed there for a while, but ran out of walls to upgrade, so I jumped to TH8 really early as well, but my main farming army was completely upgraded. Same thing at TH8, I ran out of walls to upgrade and had my army maxed so I jumped to TH9 really early. Due to having max level troops I was able to easily farm at TH9 level and because I was on all the time I didn't care about defense.
I stayed at TH9 from December through just this Week and farmed all my lego walls and most of the core of my base with lava walls. I still had a couple months of defenses left to upgrade, but decided to take the jump to TH10 for IT's and the 3rd X-bow to help out my defense in CW. I'm not farming my walls as much now, so it's still easy for me to farm enough for defensive upgrades, but the loot is a LOT less at TH10 due to the loot penalty which takes away TH8 raids.
There's no question that TH9 to TH10 is the most painful loot penalty jump because you get a lot of defensive upgrades, but not a ton of offensive upgrades that help you farm more. My farm army is exactly the same at TH10 as it was at TH9, but I now just get less from TH9 (90%) and much less from TH8 (50%).
So, I'm not sure if this helps answer your question because there really is no right answer. Sure, you get awesome defensive buildings at TH10, but if you are incapable of farming enough gold to buy any of them then you are basically hosed. I'm an above average farmer with an almost 800M GG and my gold per hour has dropped like a rock since hitting TH10.
To give you an idea. I use BAM with lvl 6 arch/barb and lvl 5 minions at TH9 in the 1800-2000 trophy range. prior to CW I could farm between 6M-8M gold per two hour boost period. This rate fell to about 2M-4M after CW due to all the inactives coming back.
I just hit TH10 on Tuesday and using the exact same strategy I've been using for months at the same trophy range 1800-2000 I farmed 2.8M gold total in 4 hours boosted. So that's the equivalent of 16 hours playing without boost. lol, it's almost laughable and I didn't realize how much of my farming in the 1800-2000 range at TH9 was dead or easy TH8 bases which are completely gone. Due to CW there are currently very few inactive TH9/10 bases in that range.
It doesn't mean you can't farm at TH10, I just have to go higher in trophy's and change my approach. I'm moving up to the
2400-2500 range (per Brandon's recommendation) to give that a whirl. Here's the catch though. I have an army that's more than capable of farming up there, so it's not a big deal. If you have lvl 5 arch/barb's you're in big trouble.
So, my advice overall to anyone that is a very active player wanting to max their base/walls as quickly as possible I say rush your main farming army barb/archer/minions and camps/rage spells as fast as possible at each level. As soon as they're maxed go to the next TH until you get to TH9. TH9 nine with appropriate level troops is by far the fastest farming army I've seen in the game from a gold per hour standpoint. Then camp at TH9 until EVERYTHING is upgraded including lava walls and then move to TH10 and move up in trophy's to farm your zap walls.
I took this approach all the way up, but went to TH10 about 6 weeks early on defense because I'm content with my lego/lava's I have and am ok farming them slower with IT's on CW defense.
I will say that from masters all the way down the vast majority of bases have rushed to their current TH level so it's not like you're a minority by any means. It's when you get the guy with lvl 1 wizard towers and wooden walls as a TH10 that people really go what the heck. :)
