It's different approaches to composing. Renoise is a "tracker" by concept and heritage. With trackers, the oldschool way of "composing" is to enter individual notes, and scrolling/skipping through the song with cursor keys, the "edit step" or the like. In this mode the keyboard will work like in typewriter mode, with keyrepeat. To achieve long notes, you'll set a note at the right place, skip the right amount of notes with cursor action, and place a note-off or a new note at that spot. You'll hear short attacks of each note you enter, and that's rather a hearing aid for composing, as many tracker artists had no real "musical" background and did their stuff "by ear". Chords are done in this way by entering the individual notes after each other in seperate channels. Just like the effect commands are entered after the notes, for example portamento is planned roughly beforehand, and programmed after entering the melody (or in between), often with a bit trial and error with adjustments in regard of the result. It's of course no "real time recording" kind of composing, but more like programming music.
One way to do what you like would be to keep a finger close to the <esc> key (or whatever is set up for arming edit mode), exit edit mode (red border will go away) and keyjazz around till the sound you want is right (when editmode is off you should be able to play long notes, chords or whatever), and then enter editmode again to program the notes to a track/pattern. Another way of entering notes is of course to hit play while edit mode is on and cursor is in the right track, and do "realtime recording", but that of course needs keyboard skills and is even harder on a typewriter keyboard! A cheap usb midi-keyboard is really worth it even for the tracker style of composing, believe me, those come at any sizes, prices, whatever. You'll by the way soon notice the problem of "dead keys" when digging deeper into chords, any typewriter other than n-key-rollover-gamer-stuff will have certain combinations where keys aren't registered.
But I think of an interesting way of entering notes as you ask this question! What about a special mode for entering notes, where when you press a note key (probably to a metronome or some rhythm-loop in the bg) it would be entered, but instead of keyrepeating or skipping you'd see a horizontal line going down the pattern at the speed of the song, stopping when you release the note, temporarily adding a note off, and waiting for the next key at the very same position? Note offs should work the same (for entering a pause), and there should be an easy accessible key for undoing the last x entries if you did wrong stuff. Thinking about this, this would be a real fun way to enter notes, halfassed between recording and classical non-realtime-stuff, and you'd get a better feel for the final sound as the notes would be played through by the exact amount of time that the final result would sport.