It may not seem like it, but the beer manufacturers' color preferences are of utmost importance.
In the early days of its origination, beer was only served in clear bottles, but the brewers soon found that when exposed as such, one of the acids in the beer reacts with sunlight and its UV rays.
The product of the reaction was a smelly and less inviting product than the original. The solution to the nagging problem was coating the bottles in brown pigment.
This limited the beer's exposure to sunlight and reduced the spoilage process that would quickly set in after the manufacturing process.
On the other hand, the green bottles, now commonly seen, didn't come into existence until the start of World War 2. During the turbulent period, brown bottles' availability reduced to a drastic degree that brewers had to find another color that helped them maintain beer's integrity and sales.
Thus the birth of the green-colored beer bottles.
To date, every beer product is packaged in either a brown or green bottle; some countries even have a more preferred color option!
Now that you know why beer bottles are either green or brown, you'll agree that it is logical. While many may prefer "fun" color options, there is no overemphasizing that maintaining the quality of the drink and ensuring that it is safe for consumption is much more important than aesthetics.