your OP question was ridiculous on it's face, that's why people keep answering in ways you don't like.
"Wouln't it be better..." Better than what exactly? What are you trying to do? Make a better scout? No, putting all extenders on will not make you a better scout. It will make you a fast weak assault.
Cal Assault Pro
- Shield = 210
- Armor = 120
- High = 4
- Low = 3
- Shield Recharge = 30
- Precision = 50
- Profile = 50
- Range = 10
Cal Scout Pro
- Shield = 130
- Armor = 70
- High = 4
- Low = 2
- Shield Recharge = 50
- Precision = 45
- Profile = 35
- Range = 20
So, just looking at EHP, you start with 130 EHP less than the Assault version. Once you have Shield and Armor core up, because they are percentage based, Scout has 160 EHP less than the Assault. With an extra low slot, the Assault can fit a Shield Regulator on the same build and get faster shield recharge.
So you always have less tank with the same modules. What is the advantage? Well, you can see Assault suits on TACNET. But Assault suits can already do that. You get a bonus to vision, so at lvl 5 you can see Scouts who don't dampen. You can also see 15m further (basically nothing without range boost, but it is something.) You also get fitting reduction on cloaks. And you are a little quicker, but as a career scout let me tell you: 5.4m/s instead of 5m/s will not help you outrun any rifle at range. To properly "speed tank" you need to see the other guy first and take advantage of surprise tactics. Since you won't be using mods to help you see better and further, you'll be missing a lot.
Meanwhile the assault Cal suit gets bonus to reload on rail weapons and 25% reduction to fitting cost on all light weapons. So he can use PRO weapons more easily, use rail rifles with better effect, while having more shield and armor.
The reason everyone is telling you to run with Range Extenders and Precision Enhancers is because those are the natural skills of the Cal Scout. You want to Maximize the skills of the suit in order to achieve a bonus that no other suit has. Tanking the scout suit completely wastes the natural benefit (anyone else can replicate your low level precision with 1 mod). But what you get in return is a suit that doesn't even have as much health as the suit you are trying to copy.