Inno doesn't see this as "abuse", else they would implement what is the easiest and most obvious 'fix': replace the city defender AI with the Continent Map AI. On the Continent, AI units do not automatically attack Rogues, which makes the rote "1 real unit + 7 Rogues" strategery potentially problematic.
So what can you do if you're being attacked and defeated by "1+7"?
Well, if you're not being Plundered, what have you lost? You get nothing for a successful defense, and you lose nothing for an unsuccessful one. If a player is just going for Tower Points, so be it.
If you are being Plundered, there's only two solutions of which I am aware:
1) Set your various Productions so as to give you the greatest chance of being there when they're done- "Collect On Time"
2) See Solution #1
Actually, #2 should be "Build a City which does not depend on structures which can be Plundered for various Production needs". There are several people here who, if they've not achieved that, are well on their way to doing so.
What does >NOT< work?
Setting a Defensive army.
Well, that's not entirely true. I do know of one player on one server that had a Defensive Army that defeated all attackers. And all he had to do to achieve that was to take his defense to >>over 800%<<. Easy as falling off a log and twice as fast.
I have one city which has a roughly 410% defense. I allocated a good deal of space to the various structures which give me that boost, space that could be used to give more FPs, more Goods, etc. And, for all the good it does, I might as well remove the defense and replace them with FP- and Goods-producers. One player with a 250% offensive boost using same-Age units defeats me every single time he attacks, using "1+7". Sorry, but that should not happen. The problem is that, along with the terrible defensive AI, it's difficult to boost your Offensive rating while defending. All of those Watchfires and Ritual Flames do nothing to boost your offense while defending. There needs to be an offensive defense structure that boosts only the offense for defending units.