Graphic design is one of the few disciplines where the amateurs and chancers make it more difficult for the professionals but it's fairly easily understood. Every business requires and uses some level of design (whether they realise it or not) but many of them know very little about how to go about assessing its quality and are consequently dazzled by off the peg design cliches which put them - or so they believe - on a par with other businesses operating at a similar level. Comparisons with accountancy and legal input miss the point entirely as these disciplines adhere to a set of clearly defined rules (as in adding up a row of figures) whereas design doesn't have any rules and consequently doesn't have any right or wrong answers. There's good and bad design, for sure, but it's largely a matter of taste and/or the lack of it. Also, I'd guess that the vast majority of design work is sold to small enterprises who don't have the advantage of the level of interest and awareness that led to the recent Gap u-turn.
In truth, design doesn't and never will have the perceived status of other business disciplines for the average user because it's a business overhead that's difficult to tangibly link to business performance. People like you and I can extol its virtues but if you put yourself in the position of the Average Joe who neither knows nor seriously cares about the nuances, it's easy to understand why so much guff passes under the radar.