Linguistics for fun and profit

The English language has 2 ways of forming the comparative/superlative. The first being to add er/est to the end of an adjective, and the second being to use more/most before the adjective. Generally speaking, short words get the first method, long words get the latter. (Click here for a more in depth explanation.) Good? Good.

But, wait a minute... Doesn't this seem incredibly arbitrary? I mean arbitrary even for English? So I started wondering if there might be some orthographic reason for the split. After all, English's long and convoluted history does often explain the illogical. Perhaps -er/est words are of Germanic origin and more/most words are of French? A brief list of adjectives indicates that this might be the case, although I have already found exceptions if so. Part of the problem with testing this hypothesis is that I don't have a good dictionary that includes the orthographies of words. Wheras Middle French and Middle English directly mingled, German's influence was much further back, so there are don't seem to be as many good cognates. This is also hampered by the fact that I don't speak German.

	French	Germanic	er/est	more/most
big	NO grand	maybe Gr:groß	YES	NO
little	NO petit	maybe Gr:klein	YES	NO
useful	probably utile	maybe Gr:nützlich	NO	YES
risky	YES risque	NO	YES	YES much more risky
interesting	YES intéressant	NO	NO	YES
popular	YES populaire	NO	NO	YES
difficult	YES difficile	NO	NO	YES
rich	YES riche	NO	YES	NO

However I haven't been able to find anything online to confirm or deny this theory. I would like to get back to the teacher who asked me that most fundamental and yet annoying of all questions: Why.

So, give me your thoughts, comments, suggestions. Pretty please?


Addendum in favor of my hypothesis:
French forms the comparative by inserting plus before the adjective and the superlative by inserting le plus. Once again, I don't speak German, a little googling makes it look like German does something more like -er/est.