Ok. After reading your post I do not think you have understood mine.
I think the issue is that WOTC doesn't know how everyone plays, cannot force players to play a certain way, and thus cannot ignore a part of the game.
I did not say players were to be forced to play any specific way or ignoring parts of the game.
Players, by default, want to be involved in the major aspects of the game. But the part of the game that takes of the most time varies from group to group. Some groups are heavy combat. Others are exploration and interaction. Others are combat and interaction.
This is repetition of everything I said just using different words.
The designers don't know how you play. Nor should they conform to your group as the model of play if they ever find out how you play. So they have to balance ever character within ever pillar. So the group that spends 2 hours fighting and 10 minutes talking has every character involve. So the group that is 2 hours of social and exploration each has every character involved. So the ⅓ each group has every character involved. Unless they use pillars, they either have to force a certain time of gameplay or suggest banlists for character types/classes that can't fit in some campaigns.
The basis does not have to go by my style of play. The class basis in the PHB should be balanced classes, but not necesarily balanced combat design.
However the DMG should offer advice for all styles of play, including a combat orientated approach -which will be followed for the group. I did not declare that any types/classes should be banned. I said favourable ADJUSTMENTS could be added to classes/character types to promote a certain style of play that the group enjoys.
For instance: Many groups added additional feats to classes in 3.5 (to speed up progression, to superceed the feat tax or to buff up a classes for combat..etc).
We added proficiency skills in 2E. Similar thing.
That is a modification to an existing class. Adjustments like those and others could be used to balance classes in combat for combat-preferred groups/campaigns.
You could do the same with skills take away - add-on, reduced or enchance spells...etc to suit the style of play for a group or campaign that wont break the system. It will be in the form of advice and a few options within the DMG to suit the style of play the group wants to run, everyone in the group, not one player or class.
Therefore mods to enchance one pillar or the other would be in the DMG to satisfy a certain style. Of course say in the
combat-mod the wizard gains a spell every spell level, he/she would lose something in the explorative or roleplaying aspect of the base class - to keep the balance. The mod is to balance the characters in combat specifically (because of the style of the campaign being run).
Hope this makes more sense now and remember I only suggested this because we have a disparity in roleplaying styles/experiences across the board and that mostly due to DMs (refer to my previous post).