First, it makes getting dressed easier while you are still learning. This is because a conservative item is very easy to combine with almost any other conservative items. They have become classics for a reason.
Second, it will help you get the highest number of matching outfits out of the clothes you buy, making the best use of your money.
Third, you will be able to wear all of these items much more often in your rotation, as they stick out less and are less likely to be remembered by others as something you have worn recently. People are much more likely to notice if you wear purple jeans twice a week than if you wear dark blue ones just as often.
Fourth, it will quickly provide you a base wardrobe that keeps you looking good every day as you begin to experiment with more personal and unique items and looks.
For example, using conservative colors that I particularly favor, if you went out and bought:
2 pairs of khaki chinos (one lighter than the other),
1 pair of dark jeans,
2 kinds of dress shirts (say 3 white and 2 light blue),
3 ties (solid charcoal, solid navy, solid burgundy),
3 sweaters (grey, navy, darker brown),
2 pairs of shoes (brown and tan),
you could blindfold yourself and pull out any pants, any shirt, any tie, any sweater and any pair of shoes and they would go together in a classic combination. If needed, you could thoughtlessly throw an outfit together very quickly every day. You would never have any item in your closet that just sits there because it does not go with any thing. Every single item in your wardrobe goes with every other single item and with any possible combination of those other items.
2 pairs of chinos (pink, yellow)
1 pair of white jeans
5 kinds of dress shirts (chartreuse, dark grey, royal blue, yellow, black)
3 ties (pink with an orange paisley pattern, navy- and yellow-striped, light blue with lime dots)
3 sweaters (bright red, black with a yellow chest stripe, purple)
2 pairs of shoes (green and teal)
First of all, props on your color courage. Nobody could accuse you of not being bold. But having spent the same amount of money as for the first sample wardrobe, you have given yourself a serious challenge every morning. What can you pair with what? You may indeed be able to come up with a harmonious if retina-burning outfit, maybe even more, but for the most part, combinations will not come easily at all. You will have many items that you never wear, because they just do not look good in the combinations available to you.
Now this is not at all to say that you should not develop a more unique or memorable style. You will certainly venture into items that more strongly express your personal style. But when you do - after some experience and learning - you will know what looks good on you, and you will have a base wardrobe of more conservative items to ground your stronger pieces. When you first begin wearing items that really call out, you want to be sure that the rest of your ensemble offers a subdued backdrop to them. If your outfit consists of nothing but statement pieces, and you have not yet developed the skill or confidence to pull it off, you risk being asked if you will clown at a friend's kid's party.
You also do not want to begin with unique items that really stand out, as you and others will get sick of them much more quickly. Taking shoes as an example, if you start off with a pair of green brogues, people will notice every time you wear them - and you will have to wear them very often since this is where you chose to begin your wardrobe building and you do not have many other options yet. Sure they will be cool on their first day, and you will get lots of comments, but you and everyone else will be sick of them before long. You also risk becoming "green shoe guy," which means your clothes are wearing you, not the other way around. The less often you wear a statement piece the more impact it retains and the less it defines your overall style. Brown derbies announce themselves less than green brogues and you will be able to wear them much more often and for a longer time without people consciously registering them and without you being embarrassed each time you trot them out.
Again, this is not about limiting yourself forever to only conservative colors and styles, it is about building a base that will allow you to wear a different outfit to work every day for many months, a base wardrobe into which you can add more and more unique items. For example, if you bought just that first list of clothes offered above (the conservative one), you would have 108 different looks! And that is assuming you wear a tie and sweater every day. If you factor in looks without ties and/or without sweaters, that minimal number of purchases would provide 192 different outfits!
Indeed they are similar if not eventually boring outfits, but they will give you time and space to work on your personal style. They provide a great base from which you can venture, intelligently, into more options. When you have well over a hundred outfits available to you from a small number of smart purchases, then going on to buy more conspicuous items you wear less frequently (to maintain their impact) is much less of a waste of money as those items now add to, instead of limiting, the number of outfits available to you. It takes time to learn and develop your style and to know how best to achieve it. Beginning your wardrobe with conservative garments gives you the time and space to make the most of the process and of the money you spend on it.
To help get the most out of your purchases now, you may also want to read this related note on the nuances of formality in Professional Attire.