Clearly the question is simplifying a pretty complex issue.
Batting is so important because it provides a level of consistency to a side. It's an undervalued commodity, consistency, but it's like a game plan in a football code; it provides reliability and allows a team to be able to trust each other and work together. As soon as the batting fails, things go haywire - plans for batsmen have to be ignored to try and get them out as quickly as possible, fields can't be employed, have to change the use of bowlers to try and have a quicker effect on the game. External factors start affecting what a team is trying to do when the batting isn't good enough.
Good teams don't need great batting line-ups, they just need consistent ones; England in 2005 is a good example of that. That's talking generally, but to take a specific example, the only time that their bowling fell apart in that series was in the third innings of the series, the one after their batting lost it.
Batting well creates its own pressure, have a look at how rarely teams get near a score of 500+ after the team batting first gets there; this despite the fact that they'll generally be batting over days 2 and 3, usually the best time for batting on a Test Match pitch.
Basically what I'm saying that while bowling wins a Test match, batting helps create a quality team over a long time, through having a core. You can replace a bowler here or there as long as the batting remains quality and consistent in output - ref: India over the past 24 months and Australia in 1999-2001.