It makes sense, as a vulnerable road user, to increase the
chance of other (motorised) road users seeing you by adopting measures such as lighter clothing with (tasteful) reflective bits, fitting and using flashing lights, and by choice, wearing a 'not a dull' helmet. Some items are most sensibly kept black/dark eg bottoms, but tights/legwarmers can have some reflective stripes or logos on and shoes/boots/overboots can do too.
There may be no evidence that this will reduce the chances of an RTI but as
@Drago has said above, it helps shut down the 'he/she hadn't made the effort to be seen' argument by observers/witnesses on site and third hand, and loved ones. You may say we shouldn't need to but we cycle in the real world. Most of us have driven up behind a cyclist and thought 'he (it's invariably a 'he') does himself no favours by dressing all in black'.
I'm saying 'chances' here: we've tragically read about cyclists who have been cleared even after they've made every effort to be visible - very hard luck:
@User33236 and
@derrick 's bh. But that doesn't mean it's not worth it at all. After all the suggestion is: use brighter coloured cycle clothing. If a top/gilet is dark I won't get it. If tights/legwarmers/shoes/boots/overboots have sensible reflective stripes or logos on I'm more likely to buy and use them, with the flashing red light by day (maybe two) (except when in a group).