Thanks for your interest, yes +2 for both attacker and defender using line.
I am not really interested in a long debate about tactics, which, as you say, are covered elsewhere both on this forum and in the literature, and by better heads than me. As I say on my blog these rules won't be everyone's cup of tea and I just put them up in case anyone was interested. They are free so you can use them or not as you wish at no cost.
However, I suggest you have misinterpreted the rules if you think I am following outdated concepts on what you call 'attack columns' (not a term I use anywhere in the rules). As a unit is a Brigade there may indeed be a mixture of lines and columns within a single unit, the key is what I call 'tactical posture' and use 'column' and 'line' as shorthand for this (something I perhaps don't make clear in the rules). A 'column' in this sense (and the sense used in the rules) may indeed be what I think you mean by 'column of lines' within a brigade supporting each other, equally it could represent purely battalion 'attack columns' (which I would suggest, although it may be heresy, actually did happen, particularly with troops not as well drilled) or battalion columns intending to deploy but leaving it too late, or a deployed front line with supporting columns in the rear. A 'line' in the sense meant in the rules is a more careful and measured formation which is emphasising one or two volleys and controlled charges over use of the bayonet and elan, but requires well drilled troops and more intensive command control to use successfully. There is a bonus for being in 'column', but only if you manage to break through your opponent. So it is more likely to work against an already shaky opponent. This gives some incentive to risk using a 'column' to break through your opponent where as otherwise everyone would simply opt for 'line'.
There is no penalty in the rules for French using 'line' in my rules so they can use it along with everyone else, who can equally use 'column' (even the British!) if they wish. What I am trying to recreate is the tactical flexibility of well drilled troops compared to less well trained ones or those with officers with less tactical flair etc.
I would suggest that 'everyone' may mostly have used line (or a 'column of lines' if you prefer) but not always, and for varying reasons. My rules attempt to reflect this and make it a viable option to use column, of course you are welcome to disagree whether it does so effectively or with my interpretation, I don't claim to be an expert but the rules work for me (as I wrote them this is only to be expected !)…
If this doesn't make sense, then I am probably not explaining it very well ! It makes sense in my head and I can only suggest you try it on the table and it might make sense then !
ponders nirvana.