But when the writing system was new, other classes were a lot more common than they are now.
[1] The categories, and examples of each, as listed in https://en.wikipedia.org/wiki/Chinese_character_classificati... :
- Direct pictorial representation of a physical object, as 水 is just a picture of water, or 马 is just a picture of a horse. (Both are ridiculous now, but recognizable in their original forms.)
- "Pictorial" representation of an abstract idea, as 上 depicts "up", 下 depicts "down", and 三 depicts "three". (These still work!)
- Semantic compounds, formed from several more basic characters all of which are used for the meaning. Apparently the subject of much debate, but examples in the spirit of the category are 森 "forest" = 木 tree + tree + tree; 好 "good" = 女 woman + 子 child; 尖 "sharp" depicting something which is 小 (small) at one end and 大 (big) at the other; 歪 "crooked" = 不 not + 正 straight; etc.
- "Loans", characters which are used solely for their phonetic content. For example, the character 英 which means "Eng"land is identical with the character 英, pronounced ying but meaning "hero". A lot of characters which were originally loans like this have subsequently developed distinctions, as 来 and 麦 have.
- Phono-semantic compounds. The topic of discussion here. As 切 qie "cut" sounds similar to 七 qi "seven", but means similarly to 刀 dao "knife", or 到 dao "to" sounds similar to 刀 dao "knife", but means similarly to 至 zhi "to", or 打 da "strike" sounds similar to 丁 ding "fourth in a sequence", but means similarly to 手 shou "hand".
- A mystery category, involving pairs of related characters, that we no longer understand. Example: 考 / 老.
This pretty well covers all the logical possibilities: direct representations, compounds involving only meaning, characters used only for sound (a compound would be superfluous there), and compounds involving meaning and sound together.
It took me all of a few seconds to look up the proverb 独木不成林 "one tree alone is not a forest". What do you think the 木 means there?
Eh, 木 is used commonly by itself.
这张椅子是用木做的。 (This chair is made of wood)
If you go back far enough, my assessment could still be correct. That is, the original standardization (oracle bones -> Qin dynasty) of Chinese characters probably had less words constructed with a sound indicator.
At the Qin dynasty, China became an empire and incorporated many new ethnic groups. It then had multiple words used in different regions (like he and jiang for river).
Pictorial and semantic characters take more thought to construct, with pictorial probably more difficult and historical. Later on, it became possible to build upon these to quickly form characters, perhaps even as a shorthand.
So it's not surprising that phono-semantic took over. This process even continued as traditional characters became simplified in modern times.
Your discussion on what characters should sound like may be more complicated. Old Chinese pronunciation is much different from Mandarin, and today's simplified characters may or may not have followed the pattern (I don't know, I didn't learn simplified).
IMO, those kinds of phono-characters were always lazy creations.