But then th is two different sounds so you need two characters
Which is why ð and þ is better
Ðe Þeolodʒical Position of Martin Luþer
Or something like that. Maybe we should bring in schwa, esh and ezh too. I mean while we're at it, we should develop a consistent manner of representing our vowel sounds.
Splitting the i of hip and the i of heel
Splitting the u of dumb and tube
Splitting the a of apple and awful (hence æsc)
Splitting the a/u/o of: lot, taught, foot, goose, and strut
Actually representing our diphthongs as diphthongs (able would be spelled eibel or eibl, for example)
Of course then you run into the inevitable problem of trying to fix English spelling: the argument for doing so is that English spelling doesn't accurately reflect English pronunciation, but English pronunciation is so varied that achieving a system that captures pronunciation accurately is essentially impossible. I mean, a really simple problem that immediately pops out in the above proposals: the vowels of lot and taught represent different sounds in some parts of America (particularly in the Midwest), and in many parts of England, but those two words rhyme for my Californian accent. pen-pin is another commonly cited example; the words represent two different vowels in my accent, but are the same vowel for many Californians.
"Knight" originally had distinct sounds for each letter, ie seven. It is now three. That is going forward.
J
This is not entirely true. The original OE word was
cniht, represented in IPA as /kniçt/ (pronounced roughly as kuh-neecht (with the ch here being equivalent to the German /ch/ as in Bach). The sound would have been very similar to the modern German Knecht (/knɛçt/) with the only difference being the vowel. This is all to say that "knight" originally had either 4 or 5 distinct phonemes, depending on whether or not you define /kn/ as an affricate, which I do. As for the modern variant, it represents 3 sounds, yes, but the short /i/ of
cniht was lengthened into the diphtong /ai/, so the time taken to say the word is technically the same as it would have been in Old English.
And if your argument is that fewer sounds = progress, then examples of us "going backwards" could be just as easily produced. OE pronunciation of cow was
cu, which was two sounds: /k/ and a geminated /u/. Now that word is represented by a /k/ and the diphthon /aʊ̯/, which is more work for your mouth and tongue. Likewise mouse is a diphthong in ModE where the OE was a simple geminated vowel:
mus.