Smoker never managed to hurt an area which was coated with haki so I don't get how exactly it would help you to even claim that he's being impressive here. What is more funny here is that Sanji did similar level damage to Vergo's face without even using haki. What kind of clueless and ridiculous logic it is? How in blue hell sending Vergo flying is more impressive than cutting someone with FBH?Smoker has Haki feats and considering damaging people with haki coated fists is more impressive than damaging someone with haki coated swords I'd say him sending Vergo flying with Haki punches is more than impressive than cutting someone with full body Haki I mean Zoro couldn't even do what Law did and slice Pica in half. (it's canon fact that defending against sharp objects with haki is harder than it is with blunt hits).
Are you seriously comparing Law's feat with that of Zoro? It was arguably Law's most powerful attack and not mention about how his DF works. On the other hand Zoro's attack was nowhere near being his most powerful and he pulled this feat purely with his haki alone. I don't really get how that sharp objects concept helps you here as both Zoro as well as Law were using swords.
Besides,You just said that defending against blunt attacks is easier than defending against sharp objects which would actually make Smoker's case even worse as he failed to defend against a blunt attack of Vergo.
Pica can use FBH so what? FBH is not a measure of strength in Haki but control in haki, we haven't seen Zoro or Luffy use FBH yet we assume they have better haki than Pica...so how is this any different to assuming Smoker has better haki?
End of the day you're not going to change your opinion due to being on the Zoro hype but the assumptions you are making make no sense at all.
Oda portrayed the point of having FBH as a godly feat for a haki user. Yes, there are people with strong haki but still didn't display FBH. But there isn't anyone one with weak haki but still able to use FBH. So being able to use FBH is impressive as it is.