I propose that Read Magic ought not to be a spell, but a skill that spellcasters have. Read Magic is almost always a sub-optimal choice to memorise, especially if casters can't cast scrolls with spells of higher level than they can memorise. At best, you are trading out one spell for another (on a scroll). There are some downtime uses for it, and some extremely uncommon edge cases where it might be handy, but it is almost always going to be the worst choice of all the spells a caster can memorise.
The main hindrance on Read Magic being memorised is the overall scarcity of spell slots. So by removing it from costing a spell slot (by turning it into a skill), we remove the main factor discouraging its use.
Here are several proposals for using Read Magic as various kinds of skills, depending on your preference.
Spellcasters have an equivalent chance to read magic as a Thief of equivalent level does to Hear Noise. (e.g. starting at 3-in-6 and increasing in Swords & Wizardry Complete)
Roll 5+ on your Decipher skill to read magical texts.
"Magical Writing" is a language. PCs who take it as a starting language may decipher spellbooks, scrolls, etc. using their % Chance to Learn New Spell. Arcane, Divine, Druidic, etc. may be separate languages as you please.
I use a combination of the last two proposals.. The first one requires the least work on the part of referees, and will probably be amenable to people who are using systems without skills and who are looking for a simple solution with a minimum of die rolling.
In Necrocarcerus, you may learn the "Magic" language, which allows you to read spellbooks, scrolls, and other magic writing of any origin without a roll. If one doesn't speak or read a language, one can use the Decipher roll. In practice, PC wizards tend to pick up the "Magic" language, while non-wizards characters will usually have to make a Decipher roll. PC languages are set by intelligence, so wizards tend to know the greatest number of languages, while skills are broadly equivalent across classes. This means that having a wizard in the party allows one to easily interpret magical writing, while without one (a rare occurrence in Necrocarcerus but admittedly possible), one is left relying on chance. I like the feeling of this.