genel (general), genellemek (to generalize), genelleme (generalization)

genellikle (usually)

You can use the suffix "-dir" when you also want to make a generalization about something. If a situation that ambiguity happens (in aspect of other tasks), you can remove this ambiguity by using "genellikle".

resmî (official, formal), daire (1circle, round (in geometry), 2house in a building (in architecture), 3office, bureau), kapanış (shutdown, closing), saat (hour), beş (five)

beş+dir

Resmî dairelerin kapanış saati beştir. (Generally, the closing time of the official bureaus is five o´clock.)

You are talking about a general case.

oğul (son), kız (1girl, 2daughter), evlenmek (to get marry), görmek (to see), güzel (nice, beautiful)

güzel+dir

Oğlunun veya kızının evlendiğini görmek güzeldir. (Generally, it is nice to see that one´s son or daughter gets married.)

köy (village), yaşamak (1to live, 2to dwell, to live, 3..4.5..6..), büyük (big, great), şehir (city), alışmak (to get used to), zor (difficult)

zor+dir

Köyde yaşamaya alıştıysan büyük şehirde yaşamak zordur. (If you have got used to live in a village, it´s difficult to live in a big city.)

You are talking about a general case/feature by the suffix "-dir".

bilgisayar (computer), yüzyıl, asır (century), büyük (big), icat (invention)

icat+ı(possessive)+dır

Bilgisayar, 20. yüzyılın en büyük icadıdır. (The computer is the biggest invention of the 20th century.)

A general information is being given about 20th century.

dil (1tongue, 2language), kendi başına (just oneself), öğrenmek (to learn), kolay (easy), değil (not)

Bir dili kendi başına öğrenmek kolay değildir. (Generally, it isn´t easy to learn a language oneself.)

doğu (1east, 2eastern), insan (human), birlikte (together)

doğu insan+ı----------------->doğu insanı (human of eastern)

birlikte+lik-------------------->birliktelik (togetherness)

birlikte+lik+ci----------------->birliktelikçi (supporting the togetherness)

Doğu insanı daha birliktelikçidir. (The human of Eastern is more collectivist.)

You compared the Western and Eastern generally, and you decided about this.

yağmurlu (rainy), hava (1sky, 2weather, 3ambiance), hız (speed), hız yapmak (to speed up (direct: to do a speed)), tehlikeli (dangerous, hazardous)

Yağmurlu havada hız yapmak tehlikelidir. (Generally, it´s dangerous to speed up in rainy weather.)

Türkiye (Turkey), siyaset (politics), her zaman (everytime), karmaşık (complicated)

Türkiye siyaseti her zaman karmaşıktır. (The politics of Turkey is complicated everytime.)

You have looked at the Turkish politics and you came to a general result and you told it.

özür dilemek (to apologize (direct: to wish a merci)), toplumsal (social), saygı (respect), ifade (1expression, 2speech)

saygı ifade+i(possessive)------->saygı ifadesi (honorific (direct: expression of respect))

Özür dilemek toplumsal bir saygı ifadesidir. (It is a social honorific to apologize.)

You added "-dir" because you wanted to remark a general rule.